Polyester composition and polyester packaging material comprising the same

ABSTRACT

The present invention relates to a polyester composition excellent in transparency, thermal stability, and flavor retention or excellent in transparency, thermal stability, flavor retention and gas barrier properties, which is obtained by blending a partially aromatic polyamide to a thermoplastic polyester, and also relates to a packaging material comprising the same. The polyester composition of the invention preferably contains an alkali metal atom in an amount of 0.1 to 300 ppm and phosphorus atom in an amount of 5 to 200 ppm. Further, it is preferable that the Color-L value of the molded article obtained by injection molding of the polyester composition of the invention at a molding temperature of 290° C. is 80.0 or more and the haze thereof is 20% or less. As the partially aromatic polyamide, an m-xylylene group-containing polyamide is preferable.

TECHNICAL FIELD

The present invention relates to a polyester composition suitably usedas a material for molded articles such as blow molded containersincluding drink bottles, films, and sheets and relates to a polyesterpackaging material comprising the same, which is excellent intransparency, thermal stability, and flavor retention and also excellentin gas barrier properties.

BACKGROUND ART

Thermoplastic polyesters such as polyethylene terephthalate(hereinafter, sometimes abbreviated as PET) are industrially highlyvaluable owing to excellence in both of mechanical properties andchemical properties and hence are widely used as fibers, films, sheets,bottles, and the like. Furthermore, since the thermoplastic polyestersare excellent in thermal resistance, transparency, and gas barrierproperties, they are particularly most suitable as materials forpackaging materials such as drink-charging containers for juices, softdrinks, carbonated drinks, and the like.

However, PET contains acetaldehyde (hereinafter, sometimes abbreviatedas AA) as a by-product at melt polycondensation. Further, PET formsacetaldehyde through thermal decomposition at thermal molding intomolded articles such as blow-molded articles to increase an acetaldehydecontent in the material of the resulting molded articles, so that tasteand smell of drinks charged in the blow-molded articles and the like areaffected.

In order to solve such problems, various measures have been hithertoadopted for reducing the acetaldehyde content in the thermoplasticpolyester molded articles. In general, there are known a method of usinga thermoplastic polyester having a reduced AA content by solid-phasepolymerization of a prepolymer obtained by melt polymerization, a methodof reducing AA formation at molding using a copolymerized thermoplasticpolyester having a lower melting point, a method of lowering a moldingtemperature at thermal molding as far as possible, a method ofdecreasing shear stress at thermal molding as far as possible, and thelike.

Recently, containers made of thermoplastic polyesters includingpolyethylene terephthalate as a representative have became used ascontainers for low flavor drinks such as mineral water and oolong tea.In the case of such drinks, these drinks are sterilized by filling whilehot or by heating after filling but it is revealed that taste and smellof the contents in these containers are not improved only by reductionof the AA content in the materials of the thermoplastic polyester moldedarticles according to the above-mentioned methods. Accordingly,improvement thereof has been desired.

As technologies for solving such problems, there have been proposed amethod of using a polyester composition obtained by adding an m-xylylenegroup-containing polyamide resin in an amount of 0.05 part by weight ormore but 1 part by weight or less per 100 parts by weight of athermoplastic polyester resin (JP 6-6662 B) and a container made of apolyester comprising a polyester composition obtained by incorporating aspecific polyamide in which the content of a terminal amino group isregulated within a certain range (JP 4-71425 B), but it becomes revealedthat the containers are sometimes still insufficient as low flavordrinks such as mineral water in view of taste and smell of the drinks.

On the other hand, it has been revealed that the thermoplastic polyesterpackaging materials mainly comprising PET are excellent in gas barrierproperties as mentioned above but it is unsatisfactory as blow-moldedarticles for contents containing compounds extremely sensitive to oxygensuch as vitamin C, so that improvement thereof has been desired.

As technologies for dissolving such problems, we have proposed athermoplastic polyester blow-molded article obtained by incorporating 1to 100 parts by weight of an m-xylylene group-containing polyamide resinper 100 parts by weight of a thermoplastic polyester resin (JP 4-54702B). However, it has been revealed that taste and smell of drinks,particularly low flavor drinks contained in blow-molded articlescomprising such polyester composition are problematic.

Further, it has been examined that a thermoplastic polyester film havinggood thermal resistance is laminated to a metal plate and the abovelaminated metal plate is utilized as metal cans mainly for foodcontainers of foods such as beverages, beer, and canned goods. In suchapplications, in order to improve flavor retention, a thermoplasticpolyester film for laminating metal plates having an acetaldehydecontent of 20 ppm or less is proposed but it is revealed that theproblems are not completely solved even when such a means is employed,so that improvement thereof has been desired.

The invention solves the above problems in conventional arts and anobject thereof is to provide a polyester composition excellent intransparency, thermal stability, and flavor retention or transparency,thermal stability, flavor retention, and gas barrier properties and alsoa polyester packaging material comprising the same.

BRIEF DESCRIPTION OF THE INVENTION

FIG. 1 is a top view of the molded plate with steps used for evaluation.

FIG. 2 is a side view of the molded plate with steps used forevaluation.

DISCLOSURE OF THE INVENTION

As a result of an examination on a polyester packaging materialexcellent in transparency and flavor retention or transparency, flavorretention, and gas barrier properties using a polyester compositioncomprising 100 parts by weight of a thermoplastic polyester and 0.1 to50 parts by weight of a partially aromatic polyamide, the presentinventors have found that the content of an alkali metal atom in thepolyester composition or the content of an alkali metal atom in thepolyester packaging material is connected with transparency and flavorretention, and thus they have accomplished the invention.

Namely, the polyester composition of the invention is a polyestercomposition comprising 100 parts by weight of a thermoplastic polyesterand 0.1 to 50 parts by weight of a partially aromatic polyamide, whereinthe content of an alkali metal atom in the polyester composition iswithin the range of 0.1 to 300 ppm.

Further, the invention is a polyester composition comprising 100 partsby weight of a thermoplastic polyester and 0.1 to 50 parts by weight ofa partially aromatic polyamide, wherein the content of phosphorus atomin the polyester composition is from 5 to 200 ppm.

Furthermore; the invention is a polyester composition comprising 100parts by weight of a thermoplastic polyester comprising a dicarboxylicacid component mainly comprising an aromatic dicarboxylic acid or anester-forming derivative thereof and a glycol component mainlycomprising ethylene glycol and 0.01 to 30 parts by weight of a partiallyaromatic polyamide, wherein the Color-L value of the molded articleobtained by injection molding of the polyester composition at a moldingtemperature of 290° C. is 80.0 or more and the haze thereof is 20% orless. In this case, the content of antimony atom is preferably 200 ppmor less. Furthermore, in the above case, the content of an alkali metalatom may be from 0.1 to 300 ppm and the content of phosphorus atom maybe from 5 to 200 ppm in the thermoplastic polyester composition.

Furthermore, it is polyester composition comprising 100 parts by weightof a thermoplastic polyester, 0.01 to 100 parts by weight of a partiallyaromatic polyamide, and 5×10⁻⁴ to 1 part by weight of an aminogroup-containing compound.

In this case, the partially aromatic polyester is preferably anm-xylylene group-containing polyamide.

In this case, the thermoplastic polyester is preferably a polyestercomprising ethylene terephthalate as a main repeating unit.

In this case, the difference (A_(t)−A₀) between the acetaldehyde content(A_(t)) (ppm) in an molded article obtained by injection molding of theabove polyester composition and the acetaldehyde content (A₀) (ppm) ofthe polyester composition before injection molding is preferably 20 ppmor less.

Herein, the acetaldehyde content (A_(t)) (ppm) in a molded articleobtained by injection molding of the polyester composition is a valuemeasured in accordance with the measuring method (7) of Example to bementioned below.

In this case, the content of a cyclic trimer derived from thethermoplastic polyester may be 0.7% by weight or less.

In this case, the increase of a cyclic trimer derived from thethermoplastic polyester during melting treatment at 290° C. for 30minutes may be 0.4% by weight or less.

Furthermore, the polyester packaging material of the invention is apolyester packaging material, which is obtained by molding the polyestercomposition mentioned above.

The packaging material may be at least any one of blow-molded articles,sheet articles, and films.

The following will specifically describe embodiments of the polyestercomposition of the invention and polyester packaging material comprisingthe same.

<Polyester>

The thermoplastic polyester for use in the invention is a crystallinethermoplastic polyester obtained mainly from an aromatic dicarboxylicacid component and-a glycol component, more preferably a thermoplasticpolyester whose acid component comprises the aromatic dicarboxylic acidunit in a ratio of 85 mol % or more, particularly preferably 90 mol % ormore, most preferably a thermoplastic polyester whose acid componentcomprises the aromatic dicarboxylic acid unit in a ratio of 95 mol % ormore.

The aromatic dicarboxylic acid component constituting the thermoplasticpolyester for use in the invention includes aromatic dicarboxylic acidssuch as terephthalic acid, 2,6-naphthalenedicarboxylic acid,diphenyl-4,4′-dicarboxylic acid, and diphenoxyethanedicarboxylic acid;functional derivatives thereof; and the like.

Further, the glycol component constituting the thermoplastic polyesterfor use in the invention includes ethylene glycol, trimethylene glycol,tetramethylene glycol, alicyclic glycols such as cyclohexanedimethanol,and the like.

The acid component to be used as a copolymerization component in theabove thermoplastic polyester includes aromatic dicarboxylic acids suchas terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalicacid, diphenyl-4,4′-dicarboxylic acid, and diphenoxyethanedicarboxylicacid; oxy acids such as p-oxybenzoic acid and oxycaproic acid andfunctional derivatives thereof; aliphatic dicarboxylic acids such asadipic acid, sebacic acid, succinic acid, glutaric acid, and dimer acidand functional derivatives thereof; alicyclic dicarboxylic acids such ashexahydroterephthalic acid, hexahydroisophthalic acid, andcyclohexanedicarboxylic acid and functional derivatives thereof; and thelike.

The glycol component to be used as a copolymerization component in theabove thermoplastic polyester includes aliphatic glycols such asethylene glycol, trimethylene glycol, tetramethylene glycol, diethyleneglycol, and neopentyl glycol; alicyclic glycols such ascyclohexanedimethanol; aromatic glycols such as1,3-bis(2-hydroxyethoxy)benzene, bisphenol A, and alkylene oxide adductsof bisphenol A; polyalkylene glycols such as polyethylene glycol andpolybutylene glycol; and the like

Furthermore, within the range where the thermoplastic polyester issubstantially linear, a polyfunctional compound such as trimelliticacid, trimesic acid, pyromellitic acid, tricarballylic acid, glycerin,pentaerythritol, or trimethylolpropane may be copolymerized and also, amonofunctional compound such as benzoic acid or naphthic acid may becopolymerized.

One preferable example of the thermoplastic polyester for use in theinvention is a thermoplastic polyester wherein its main repeating unitis constituted by ethylene terephthalate, more preferred is a linearcopolymerized thermoplastic polyester containing an ethyleneterephthalate unit in a ratio of 85 mol % or more and containingisophthalic acid, 2,6-dinaphthalenedicarboxylic acid,1,4-cyclohexanedimethanol, and/or the like as copolymerizationcomponent(s), and particularly preferred is a linear thermoplasticpolyester containing an ethylene terephthalate unit in a ratio of 95 mol% or more.

Examples of these linear thermoplastic polyesters include polyethyleneterephthalate (hereinafter, abbreviated as PET), poly(ethyleneterephthalate-ethylene isophthalate) copolymer, poly(ethyleneterephthalate-1,4-cyclohexanedimethylene terephthalate) copolymer,poly(ethylene terephthalate-ethylene 2,6-naphthlate) copolymer,poly(ethylene terephthalate-dioxyethylene terephthalate) copolymer, andthe like.

Further, one preferable example of the thermoplastic polyester for usein the invention is a thermoplastic polyester wherein its main repeatingunit is constituted by ethylene-2,6-naphthalate, more preferred is alinear copolymerized thermoplastic polyester containing anethylene-2,6-naphthalate unit in a ratio of 85 mol % or more, andparticularly preferred is a linear thermoplastic polyester containing anethylene-2,6-naphthalate unit in a ratio of 95 mol % or more.

Examples of these linear thermoplastic polyesters includepolyethylene-2,6-naphthalate, poly(ethylene-2,6-naphthalate-ethyleneterephthalate) copolymer, poly(ethylene-2,6-naphthalate-ethyleneisophthalate) copolymer,poly(ethylene-2,6-naphthalate-dioxyethylene-2,6-naphthlate) copolymer,and the like.

Other preferable examples of the thermoplastic polyester for use in theinvention include a linear thermoplastic polyester containing apropylene terephthalate unit in a ratio of 85 mol % or more, a linearthermoplastic polyester containing a 1,4-cyclohexanedimethyleneterephthalate unit in a ratio of 85 mol % or more, or a linearthermoplastic polyester containing a butylene terephthalate unit in aratio of 85 mol % or more.

The thermoplastic polyesters mentioned above can be produced accordingto production processes hitherto known. Namely, in the case of PET, itcan be produced according to a process of direct esterification whereinterephthalic acid, ethylene glycol, and, if necessary, the abovecopolymerization component(s) are directly reacted and water is removedby evaporation to effect esterification and then polycondensation iscarried out under reduced pressure using one or more compounds selectedfrom an Sb compound, a Ge compound, a Ti compound, and an Al compound asa polycondensation catalyst or a process of transesterification whereindimethyl terephthalate, ethylene glycol, and, if necessary, the abovecopolymerization component(s) are reacted in the presence of atransesterification catalyst and methyl alcohol is removed byevaporation to effect transesterification and then polycondensation iscarried out under reduced pressure using one or more compounds selectedfrom an Sb compound, a Ge compound, a Ti compound, and an Al compound asa polycondensation catalyst.

Furthermore, solid-phase polymerization may be carried out in order toincrease intrinsic viscosity and lower the contents of formaldehyde andacetaldehyde and the content of cyclic ester trimer.

The above esterification reaction, transesterification reaction, meltpolycondensation reaction, and solid-phase polymerization reaction maybe carried out in a batch-type reaction apparatus or may be carried outin a continuous reaction apparatus. In any of these methods, the meltpolycondensation reaction may be carried out in one step or separatelyin multi steps. The solid-phase polymerization reaction can be carriedout in a batch-type reaction apparatus or a continuous reactionapparatus as in the case of the melt polycondensation reaction. The meltpolycondensation and solid-phase polymerization may be carried outsuccessively or separately.

The Sb compound for use in the production of the thermoplastic polyesterfor use in the invention includes antimony trioxde, antimony acetate,antimony tartrate, antimony potassium tartrate, antimony oxychloride,antimony glycolate, antimony pentoxide, triphenylantimony, and the like.The Sb compound is preferably added so as to be 250 ppm as an Sbremaining amount in a formed polymer. Preferable upper limit is 200 ppm,more preferable upper limit is 190 ppm, and more preferable upper limitis 180 ppm. When the content of the antimony atom remaining in thepolyester for use in the invention is more than 250 ppm, a blackishappearance is apt to occur in the molded articles obtained from thepolyester composition of the invention and transparency thereof is poorin some cases. Preferable lower limit is 50 ppm and more preferablelower limit is 70 ppm. When it is less than 50 ppm, the polycondensationreaction of the polyester proceeds slowly and productivity becomes poor,so that the case is sometimes not practical.

The Ge compound for use in the production of the thermoplastic polyesterfor use in the invention includes amorphous germanium dioxide,crystalline germanium dioxide, germanium chloride, germaniumtetraethoxide, germanium tetra-n-butoxide, germanium phosphite, and thelike. In the case that the Ge compound is used, the amount to be used isfrom 5 to 150 ppm, preferably from 10 to 100 ppm, more preferably from15 to 70 ppm as a Ge remaining amount in the thermoplastic polyester.

The Ti compound for use in the production of the thermoplastic polyesterfor use in the invention includes tetraalkyl titanates such astetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate,and tetra-n-butyl titanate and partial hydrolysates thereof; titanyloxalate compounds such as titanyl oxalate, titanyl ammonium oxalate,titanyl sodium oxalate, titanyl potassium oxalate, titanyl calciumoxalate, and titanyl strontium oxalate; titanium trimellitate, titaniumsulfate, titanium chloride, and the like. The Ti compound is added so asto be in the range of 0.1 to 10 ppm as a Ti remaining amount in a formedpolymer.

Further, the Al compound for use in the production of the thermoplasticpolyester for use in the invention specifically includes carboxylatesalts such as aluminum formate, aluminum acetate, basic aluminumacetate, aluminum propionate, aluminum oxalate, aluminum acrylate,aluminum laurate, aluminum stearate, aluminum benzoate, aluminumtrichloroacetate, aluminum lactate, aluminum citrate, and aluminumsalicylate; inorganic acid salts such as aluminum chloride, aluminumhydroxide, aluminum hydroxide chloride, aluminum polychloride, aluminumnitrate, aluminum sulfate, aluminum carbonate, aluminum phosphate, andaluminum phosphonate; aluminum alkoxides such as aluminum methoxide,aluminum ethoxide, aluminum n-propoxide, aluminum iso-propoxide,aluminum n-butoxide, and aluminum t-butoxide; aluminum chelate compoundssuch as aluminum acetylacetonate, aluminum acetylacetate, aluminumethylacetoacetate, and aluminum ethylacetoacetate di-isopropoxide;organoaluminum compounds such as trimethylaluminum and triethylaluminumand partial hydrolysates thereof; aluminum oxide, and the like Of these,carboxylate salts, inorganic acid salts and chelate compounds arepreferred. Of these, furthermore, basic aluminum acetate, aluminumchloride, aluminum hydroxide, aluminum hydroxide chloride, and aluminumacetylacetonate are particularly preferred. The Al compound is added soas to be in the range of 5 to 200 ppm as a Al remaining amount in aformed polymer.

Further, in the production of the thermoplastic polyester for use in theinvention, an alkali metal compound or an alkaline earth metal compoundmay be used in combination. The alkali metal compound or the alkalineearth metal compound includes carboxylate salts such as acetates,alkoxides, and the like of these elements and is added to a reactionsystem as a powder, an aqueous solution, an ethylene glycol solution, orthe like. The alkali metal compound or the alkaline earth metal compoundis added so as to be in the range of 1 to 50 ppm as a remaining amountof these elements in a formed polymer.

The above catalyst compound can be added at any stage of the abovethermoplastic polyester-forming reaction step.

Further, various phosphorus compounds can be used as stabilizers. Thephosphorus compounds for use in the invention include phosphoric acid,phosphorous acid, phosphonic acid, and derivatives thereof. Specificexamples include phosphoric acid, trimethyl phosphate, triethylphosphate, tributyl phosphate, triphenyl phosphate, monomethylphosphate, dimethyl phosphate, monobutyl phosphate, dibutyl phosphate,phosphorous acid, trimethyl phosphite, triethyl phosphite, tributylphosphite, methylphosphonic acid, dimethyl methylphosphonate, dimethylethylphosphonate, dimethyl phenylphosphonate, diethyl phenylphosphonate,diphenyl phenylphosphonate, and the like, and they may be used solely ortwo or more of them may be used in combination. The phosphorus compoundmay be added at any stage of the above thermoplastic polyester-formingreaction step so as to be in the range of 5 to 100 ppm as a phosphorusremaining amount in a formed polymer.

The intrinsic viscosity of the thermoplastic polyester, particularly thethermoplastic polyester comprising ethylene terephthalate as a mainrepeating unit is in the range of preferably 0.55 to 1.50 dl/g, morepreferably 0.58 to 1.30 dl/g, further preferably 0.60 to 0.90 dl/g. Whenthe intrinsic viscosity is less than 0.55 dl/g, mechanical properties ofthe resulting packaging material or the like are poor. Further, in thecase that it exceeds 1.50 dl/g, there arise problems that freelow-molecular-weight compounds affecting flavor retention increase,packaging material is colored yellow, and the like since a resintemperature becomes high at its melting by means of a molding machine orthe like to induce severe thermal decomposition.

Further, the intrinsic viscosity of the thermoplastic polyester for usein the invention, particularly the thermoplastic polyester comprisingethylene-2,6-naphthalate as a main repeating unit is in the range of0.40 to 1.00 dl/g, preferably 0.42 to 0.95 dl/g, further preferably 0.45to 0.90 dl/g. When the intrinsic viscosity is less than 0.40 dl/g,mechanical properties of the resulting packaging material or the likeare poor. Further, in the case that it exceeds 1.00 dl/g, there ariseproblems that free low-molecular-weight compounds affecting flavorretention increase, packaging material is colored yellow, and the likesince a resin temperature becomes high at its melting by means of amolding machine or the like to induce severe thermal decomposition.

The shape of chips of the thermoplastic polyester for use in theinvention may be any of cylindrical, rectangular, spherical, flat, orthe like shape. Its average particle size is in the range of usually 1.3to 5 mm, preferably 1.5 to 4.5 mm, further preferably 1.6 to 4.0 mm. Forexample, in the case of cylindrical shape, chips having a length of 1.3to 4 mm and a diameter of 1.3 to 4 mm are practical. In the case ofspherical particles, it is practical that the maximum particle size isfrom 1.1 to 2.0 times larger than the average particle size and theminimum particle size is 0.7 time or more compared to the averageparticle size. Further, the weight of the chips is practically in therange of 10 to 30 mg/chip.

Further, the content of the cyclic ester trimer in the thermoplasticpolyester for use in the invention is preferably 0.70% by weight orless, more preferably 0.60% by weight or less, further preferably 0.50%by weight or less, particularly preferably 0.45 or less. In the casethat a thermally resistant blow-molded article or the like is moldedfrom the thermoplastic polyester of the invention, when a polyesterhaving a cyclic ester trimer content exceeding 0.70% by weight is used,the attachment of oligomers onto heated mold surface rapidly increasesand transparency of the resulting blow-molded article becomes extremelybad. Further, in the case of preparing a sheet-like article, only asheet-like article having bad surface conditions and poor transparencyis obtained owing to severe fouling of cooling rolls and touch rolls. Inthis connection, the cyclic ester trimer means a cyclic ester trimercomprising terephthalic acid and ethylene glycol.

Further, the thermoplastic polyester for use in the invention preferablyexhibits an increase of the cyclic ester trimer of 0.4% by weight duringmelt treatment at 290° C. for 30 minutes. Such a polyester can beproduced by deactivating a polycondensation catalyst remaining in thepolyester obtained after melt polycondensation or after solid-phasepolymerization.

As a method for deactivating the polycondensation catalyst in thepolyester, there may be mentioned a method of bringing the polyesterchips into contact with water or water vapor or a gas containing watervapor after melt polycondensation or after solid-phase polymerization.

These methods are described in detail in JP 3-174441 A, JP 2000-72867 A,and so on, and the production can be effected using the methods.

Further, as an alternative method for deactivating the polycondensationcatalyst, there may be mentioned a method of deactivating thepolymerization catalyst by adding a phosphorus compound to a melt of thepolyester after melt polycondensation or after solid-phasepolymerization and mixing them.

In the case of a melt polycondensation polyester, there may be mentioneda method of deactivating the polycondensation catalyst by mixing thepolyester after completion of the melt polycondensation reaction with apolyester resin containing the phosphorus compound in an instrument suchas a line mixer capable of mixing them at a melt state.

Further, as methods of blending a solid phase polymerization polyesterwith the phosphorus compound, there may be mentioned a method ofdry-blending the solid-phase polymerization polyester with a phosphoruscompound and a method of deactivating the polycondensation catalyst byblending the polyester with a predetermined amount of a phosphoruscompound by mixing a polyester masterbatch chips blended with thephosphorus compound through melt-kneading and solid-phase polymerizationpolyester chips, followed by melting them in an extruder or a moldingmachine.

The phosphorus compound to be used includes phosphoric acid, phosphorousacid, phosphonic acid, and derivatives thereof. Specific examplesinclude phosphoric acid, trimethyl phosphate, triethyl phosphate,tributyl phosphate, triphenyl phosphate, monomethyl phosphate, dimethylphosphate, monobutyl phosphate, dibutyl phosphate, phosphorous acid,trimethyl phosphite, triethyl phosphite, tributyl phosphite,methylphosphonic acid, dimethyl methylphosphonate, dimethylethylphosphonate, dimethyl phenylphosphonate, diethyl phenylphosphonate,diphenyl phenylphosphonate, and the like, and they may be used solely ortwo or more of them may be used in combination.

In general, the thermoplastic polyester contains a considerable amountof a fine powder, namely fine, which is generated during the productionstep and whose copolymerization components and content of thecopolymerization components are identical to those of the thermoplasticpolyester chips. Such a fine has a property of acceleratingcrystallization of the thermoplastic polyester. When it is present in alarge amount, there arise problems that transparency of the moldedarticles molded from the above polyester composition containing such afine becomes extremely bad and, in the case of a bottle, a shrunkenamount at crystallization of the bottle mouth part exceeds a prescribedrange, so that the bottle cannot be hermetically sealed with a cap.Therefore, it is desirable that the content of the fine in thethermoplastic polyester for use in the invention is 1000 ppm or less,preferably 500 ppm or less, more preferably 500 ppm or less, furtherpreferably 300 ppm or less, particularly preferably 200 ppm or less,most preferably 100 ppm or less.

<Partially Aromatic Polyamide>

The partially aromatic polyamide according to the invention is apolyamide comprising a unit derived-from an aliphatic dicarboxylic acidand an aromatic diamine as a main constituting unit or a polyamidecomprising a unit derived from an aromatic dicarboxylic acid and analiphatic diamine as a main constituting unit.

The aromatic dicarboxylic acid component constituting the partiallyaromatic polyamide according to the invention includes terephthalicacid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid,diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid, andfunctional derivatives thereof.

As the aliphatic dicarboxylic acid component constituting the partiallyaromatic polyamide according to the invention, a linear aliphaticdicarboxylic acid is preferred and a linear aliphatic dicarboxylic acidcontaining an alkylene group having 4 to 12 carbon atoms is particularlypreferred. Examples of the linear aliphatic dicarboxylic acid includeadipic acid, sebacic acid, malonic acid, succinic acid, glutaric acid,pimelic acid, suberic acid, azelaic acid, undecanoic acid, undecanedioicacid, dodecanedioic acid, dimer acid, and functional derivativesthereof.

The aromatic diamine component constituting the partially aromaticpolyamide according to the invention includes m-xylylenediamine,p-xylylenediamine, p-bis-(2-aminoethyl)benzene, and the like.

The aliphatic diamine component constituting the partially aromaticpolyamide according to the invention is an aliphatic diamine having 2 to12 carbon atoms or a functional derivative thereof. The aliphaticdiamine may be a linear aliphatic diamine or a chain-like aliphaticdiamine having a branch. Specific examples of such a linear aliphaticdiamine include aliphatic diamines such as ethylenediamine,1-methylethylenediamine, 1,3-propylenediamine, tetramethylenediamine,pentamethylenediamine, hexamethylenediamine, heptamethylenediamine,octamethylenediamine, nonamethylenediamine, decamethylenediamine,undecamethylenediamine, and dodecamethylenediamine.

Further, as the dicarboxylic acid component constituting the partiallyaromatic polyamide according to the invention, an alicyclic dicarboxylicacid can be used in addition to the aromatic dicarboxylic acid and thealiphatic dicarboxylic acid. The alicyclic dicarboxylic acid includesalicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid,hexahydroterephthalic acid and hexahydroisophthalic acid,

furthermore, as the diamine component constituting the partiallyaromatic polyamide according to the invention, an alicyclic diamine canbe used in addition to the aromatic diamine and the aliphatic diamine.The alicyclic diamine includes alicyclic diamines such ascyclohexanediamine and bis-(4,4′-aminohexyl)methane.

In addition to the above diamines and dicarboxylic acids, use can bemade of lactams such as ε-caprolactam and lauroylactam, aminocarboxylicacids such as aminocaproic acid and aminoundecanoic acid, aromaticaminocarboxylic acids such as p-aminomethylbenzoic acid, and the like ascopolymerization components. In particular, use of ε-caprolactam isdesirable.

A preferable example of the partially aromatic polyamide according tothe invention is a m-xylylene group-containing polyamide containing aconstituting unit derived from m-xylylenediamine or a mixedxylylenediamine containing m-xylylenediamine and p-xylylenediamine whoseamount is 30% or less of the whole amount and an aliphatic dicarboxylicacid in a ratio of at least 20 mol % or more, further preferably 30 mol% or more, particularly preferably 40 mol % or more in the molecularchain.

Further, the partially aromatic polyamide according to the invention maycontain a constituting unit derived from a polybasic carboxylic acidhaving tribasicity or higher basicity, such as trimellitic acid andpyromellitic acid, within a range where the polyamide is substantiallylinear.

Examples of these polyamides include homopolymers such aspoly(m-xylyleneadipamide), poly(m-xylylenesebacamide), andpoly(m-xylylenesberamide), and m-xylylenediamine/adipic acid/isophthalicacid copolymer, m-xylylene/p-xylyleneadiamide copolymer,m-xylylene/p-xylylenepiperamide copolymer,m-xylylene/p-xylyleneazelamide copolymer, m-xylylenediamine/adipicacid/isophthalic acid/ε-caprolactam copolymer, m-xylylenediamine/adipicacid/isophthalic acid/ω-aminocaproic acid copolymer, and the like.

Further, other preferable example of the partially aromatic polyamideaccording to the invention is a polyamide containing a constituting unitderived from an aliphatic diamine and at least one acid selected fromterephthalic acid and isophthalic acid in a ratio of at least 20 mol %or more, further preferably 30 mol % or more, particularly preferably 40mol % or more in the molecular chain.

Examples of these polyamides include polyhexamethyleneterephthalimide,polyhexamethyleneisophthalamide, hexamethylenediamine/terephthalicacid/isophthalic acid copolymer, polynanomethyleneterephthalamide,polynanomethyleneisophthalamide, nanomethylenediamine/terephthalicacid/isophthalic acid copolymer, nanomethylenediamine/terephthalicacid/adipic acid copolymer, and the like.

Further, other preferable example of the partially aromatic polyamideaccording to the invention is a polyamide containing a constituting unitderived from an aliphatic diamine and at least one acid selected fromterephthalic acid and isophthalic acid, which is obtained using, inaddition to the aliphatic diamine and at least one acid selected fromterephthalic acid and isophthalic acid, a lactam such as ε-caprolactamor laurolactam, an aminocarboxylic acid such as aminocaproic acid oraminoundecanoic acid, an aromatic aminocarboxylic acid such asp-aminomethylbenzoic acid as a copolymerization component in a ratio ofat least 20 mol % or more, further preferably 30 mol %, particularlypreferably 40 mol % or more in the molecular chain.

Examples of these polyamides include hexamethylenediamine/terephthalicacid/ε-caplolactam copolymer, hexamethylenediamine/isophthalicacid/ε-caplolactam copolymer, hexamethyvlnpdiamine/terephthalicacid/adipic acid/ε-caplolactam copolymer, and the like.

The above partially aromatic polyamide can be produced according to amethod for polycondensation at a melt state by heating an aqueoussolution of an aminocarboxylic acid salt formed from an diamine and adicarboxylic acid under elevated pressure and under normal pressurewhile removing water and water formed during the polycondensationreaction, a method for polycondensation by heating an diamine and andicarboxylic acid to react them directly at a melt state under normalpressure or successively under vacuum, or the like method. Further, bysolid-phase polymerization of chips of the above polyamides obtained bythese melt polymerization reactions, partially aromatic polyamideshaving higher viscosity can be obtained.

The above polycondensation reactions for the partially aromaticpolyamides may be carried out in a batch-type reaction apparatus or in acontinuous reaction apparatus.

At the production of the partially aromatic polyamide for use in theinvention, it is preferable to add an alkali metal-containing compoundrepresented by the following chemical formula (A) in order to enhancethermal stability and to prevent gel formation. The content of thealkali metal atom in the above partially aromatic polyamide ispreferably within the range of 1 to 1000 ppm. It is desirable that thelower limit of the content of the alkali metal atom in the abovepartially aromatic polyamide is 10 ppm, further 20 ppm, particularly 30ppm or more and it is desirable that the upper limit is 900 ppm, further800 ppm, particularly 750 ppm.Z-OR₈  (A)wherein Z represents an alkali metal and R₈ represents a hydrogen atom,an alkyl group, an aryl group, a cycloalkyl group, —C(O)CH₃, or —C(O)OZ′wherein Z′ represents a hydrogen atom or an alkali metal.

The alkali compound represented by the chemical formula (A) includessodium hydroxide, sodium methoxide, sodium ethoxide, sodium propoxide,sodium butoxide, potassium methoxide, lithium methoxide, sodium acetate,sodium carbonate, alkaline earth compounds including alkaline earthmetals, and the like but is not limited to these compounds.

Further, at the production of the above partially aromatic polyamide, itis preferable to effect the polymerization with adding a phosphoruscompound as a stabilizer for preventing gel formation owing to thermaldegradation.

When the content of phosphorus atom derived from the above phosphoruscompound in the partially aromatic polyamide for use in the invention isreferred to as X, X is preferably in the range of 0<X≦500 ppm. The lowerlimit is preferably 0.1 ppm, more preferably 1 ppm, further preferably 5ppm. The upper limit is preferably 400 ppm, more preferably 300 ppm,further preferably 250 ppm. When X is 0, i.e., no phosphorus atom iscontained, the effect of preventing gel formation is poor. On the otherhand, when X is larger than the above range, a limit for the effect ofpreventing gel formation is observed and also the case is noteconomical. Furthermore, there is a case that Sb in the catalyst isreduced to metal Sb by a reducing action of phosphorus to decrease thecolor-L value. In order to increase the color-L value, it is preferableto lower the phosphorus content in the case that an Sb amount is large.

As the phosphorus compound to be added into the above partially aromaticpolyamide, at least one compound selected from compounds represented bythe following chemical formulae (B-1) to (B-4):

wherein R₁ to R₇ each represents a hydrogen atom, an alkyl group, anaryl group, a cycloalkyl group, or an arylalkyl group and X₁ to X₅ eachrepresents a hydrogen atom, an alkyl group, an aryl group, a cycloalkylgroup, an arylalkyl group, or an alkali metal, or one of X₁ to X₅ andone of R₁ to R₇ may be combined with each other to form a ringstructure.

The phosphinic acid represented by the chemical formula (B-1) includesdimtheylphoshinic acid, phenylmethylphosphinic acid, hypophosphorousacid, sodium hypophosphite, potassium hypophosphite, lithiumhypophosphite, ethyl hypophosphite, a compound of

and hydrolysates thereof, condensates of the above phosphinic acidcompounds, and the like.

The phosphonous acid represented by the chemical formula (B-2) includesphenylphosphonous acid, sodium phenylphosphonite, potassiumphenylphosphonite, lithium phenylphosphonite, ethyl phenylphosphonite,and the like.

The phosphonic acid represented by the chemical formula (B-3) includesphenylphosphonic acid, ethylphosphonic acid, sodium phenylphosphonate,potassium phenylphosphonate, lithium phenylphosphonate, diethylphenylphosphonate, sodium ethylphosphonate, potassium ethylphosphonate,and the like.

The phosphorous acid represented by the chemical formula (B-4) includesphosphorous acid, sodium hydrogen phosphite, sodium-phosphite, triethylphosphite, triphenyl phosphite, pyrophosphorous acid, and the like.

The content of total alkali metals in the partially aromatic polyamidefor use in the invention (total Amount of the alkali metal atomcontained in the above phosphorus stabilizer and the alkali metal atomcontained in the above alkali metal compound) is preferably from 1.0 to6.0 molar equivalents to the content of the phosphorus atom in thepolyamide. The lower limit is more preferably 1.5 molar equivalents,further preferably 2.0 molar equivalents, particularly preferably 2.3molar equivalents, most preferably molar equivalents. The upper limit ismore preferably 5.5 molar equivalents, further preferably 5.0 molarequivalents. When the content of total alkali metals is less than 1.0molar equivalent to the content of the phosphorus atom, gel formation isapt to be accelerated. On the other hand, when the content of totalalkali metals is larger than 6.0 molar equivalents to the content of thephosphorus atom, a polymerization rate becomes low, the viscosity doesnot sufficiently increase, and gel formation is accelerated all the moreparticularly in a system under reduced pressure, so that the case is noteconomical.

The compounds represented by the above chemical formulae (B-1) to (B-4)for use in the invention may be used solely but they are preferably usedin combination since thermal stability of the polyester composition isimproved.

For blending the partially aromatic polyamide for use in the inventionwith the above phosphorus compound or the above alkali metal-containingcompound, these compounds may be added to raw materials before polyamidepolymerization or during the polymerization or may be melt-mixed intothe above polymer.

Further, these compounds may be added at once or may be addedseparately.

The relative viscosity of the partially aromatic polyamide for use inthe invention is in the range of 1.3 to 4.0, preferably 1.5 to 3.0, morepreferably 1.7 to 2.5, and further preferably 1.8 to 2.0. When therelative viscosity is 1.3 or less, the molecular weight is too small, sothat mechanical properties of the packaging material comprising thepolyester composition of the invention are sometimes poor. To thecontrary, when the relative viscosity is 4.0 or more, polymerization ofthe above polyamide requires a long time, which sometimes not onlycauses deterioration and undesirable coloring of the polymer but alsoreduces productivity resulting in a factor of cost increase.

When the concentration (μmol/g) of the terminal amino group in thepartially aromatic polyamide for use in the invention is referred to asAEG and the concentration (μmol/g) of the terminal carboxyl group in thepartially aromatic polyamide is preferred to as CEG, the ratio of AEG toCEG (AEG/CEG) is preferably 1.05 or more. When the ratio of theconcentration of the terminal amino group to the terminal carboxyl group(AEG/CEG) in the partially aromatic polyamide is less than 1.05, flavorretention of the polyester packaging material of the invention is poorand hence such a polyester packaging material is sometimes poor inpracticality as containers for low flavor drinks. When the ratio of theconcentration of the terminal amino group to the terminal carboxyl group(AEG/CEG) in the partially aromatic polyamide exceeds 20, the resultingpolyester packaging material is severely colored and has no commercialvalue, so that the case is not preferable.

It is noted that the above partially aromatic polyamide contains cyclicoligomers such as a cyclic amide monomer, a cyclic amid dimer, a cyclicamide trimer, and a cyclic amide tetramer comprising the dicarboxylicacid and the diamine to be used as starting materials, unreactedmonomers such as the above dicarboxylic acid and the above diamine, andlinear oligomers such as a linear dimer and a linear trimer comprisingthe above dicarboxylic acid and the above diamine. The contents of themmay vary depending on the polycondensation method, the polycondensationconditions, or the molecular weight of the polyamide formed, but in oneexample; the contents are as follows: from 0.2 to 2.0% by weight for thecyclic amide monomer, from 0.1 to 2.0% by weight for the cyclic amidedimer, from 0.1 to 1.0% by weight for the cyclic amide trimer, and from0.005 to 0.5% by weight for the cyclic amide tetramer, an order of 1 to5000 ppm for linear oligomers, and an order of 0.1 to 2000 ppm forunreacted monomers.

Herein, in the case that the partially aromatic polyamide is a polyamidecomprising m-xylylenediamine and adipic acid, the chemical formula ofthe cyclic oligomers is represented by the following formula and thecase where n is 1 is a cyclic amide monomer:

wherein n represents an integer of 1 to 4.

It is preferable that the content of the cyclic amide monomers in thepartially aromatic polyamide is 0.9% by weight or less, preferably 0.8%by weight or less, further preferably 0.6% by weight or less.

When a partially aromatic polyamide having a cyclic amide monomercontent exceeding 0.9% by weight is used, flavor retention of contentsfilled into a molded article obtained therefrom becomes bad and moldfouling is very severe which is generated by attaching foreign matter tothe inner surface of the mold during the molding of the molded articleand the exhaust outlet and exhaust pipe of gases of the mold. In thisconnection, the content of the cyclic amide monomer herein means thecontent of the cyclic amide monomer contained in the polyamide. Thelower limit of the content of the cyclic amide monomer is preferably0.001 ppm from the economical viewpoint and the like. The cyclic amidemonomer can be measured by a high-performance liquid chromatography tobe described below.

The partially aromatic polyamide having a cyclic amide monomer contentof 0.9% by weight or less can be, for example, produced as follows.Namely, the polyamide can be obtained by subjecting the polyamide chipsobtained according to the above production process to heat treatment orextraction treatment with an alcohol such as methanol or ethanol or anaqueous methanol solution or an aqueous ethanol solution.

For example, the above amide chips are placed in a tank for heattreatment and 50% aqueous ethanol solution is added thereto, followed bytreatment at about 50 to 60° C., the resulting chips being subjected tomolding. Such heat treatment or the like may be carried out in abatch-type treating apparatus or in a continuous treating apparatus.

Further, the partially aromatic polyamide for use in the invention canbe also obtained by changing the adding ratio of the diamine such asm-xylylenediamine to the dicarboxylic acid such as adipic acid at thepolycondensation or by changing polycondensation conditions.

The tertiary nitrogen content of the partially aromatic polyamideconstituting the polyester composition of the invention is preferably2.0 mol % or less, more preferably 1.5 mol % or less, further preferably1.0 mol % or less. A molded article obtained using a polyestercomposition containing a partially aromatic polyamide having a tertiarynitrogen content exceeding 2.0 mol % contains colored foreign matter dueto gelled matter and is sometimes poor in color. Particularly in anoriented film or a biaxially oriented blow-molded article, the partwhere gelled matter is present is not normally oriented and remainsthick, which causes unevenness of thickness. Thus, a large number ofmolded articles having no commercial value are sometimes produced todecrease process yields and, in the worst case, only the molded articleshaving no commercial value are obtained.

Further, the upper limit of the tertiary nitrogen content is preferably0.001 mol %, more preferably 0.01 mol %, further preferably 0.05 mol %,particularly preferably 0.1 mol % for the reason of production. At theproduction of the partially aromatic polyamide having a tertiarynitrogen content of less than 0.001 mol %, there may sometimes ariseproblems in productivity, i.e., use of highly purified raw materials,necessity of a large amount of an anti-degradation agent, necessity ofmaintenance of a low polymerization temperature, and the like.

In this connection, the tertiary nitrogen herein means both of nitrogenbased on an imino compound and nitrogen based on a tertiary amide andthe tertiary nitrogen content is a content expressed by molar ratio (mol%) relative to the nitrogen based on a secondary amide (—NHCO—: an amideconstituting a normal main chain).

In the case that a large number of imino groups are present in thepolyamide, there is a case that the imino group moiety reacts with theterminal of the dicarboxylic acid to generate gelled mater and when alarge amount of the tertiary amide is present in the polyamide, thegelled matter sometimes forms in a large amount.

The shape of chips of the partially aromatic polyamide for use in theinvention may be any of cylindrical, rectangular, spherical, flat plate,or the like shape. Its average particle size is in the range of usually1.0 to 5 mm, preferably 1.2 to 4.5 mm, further preferably 1.5 to 4.0 mm.For example, in the case of cylindrical shape, chips having a length of1.0 to 4 mm and a diameter of 1.0 to 4 mm are practical. In the case ofspherical particles, it is practical that the maximum particle size isfrom 1.1 to 2.0 times larger than the average particle size and theminimum particle size is 0.7 time or more compared to the averageparticle size. Further, the weight of the chips is practically in therange of 5 to 30 mg/chip.

<Polyester Composition>

The polyester composition of the invention may have a shape obtained bymolding a melt mixture of the thermoplastic polyester and the partiallyaromatic polyamide. The state obtained by molding is not limited tostrand-shape, chip-shape, and cylindrical shape and may be blow-moldedarticle shape, sheet-shape, film-shape, and pulverized matter thereofand the shape is not particularly limited.

Further, the polyester composition may be a dry blend of thethermoplastic polyester and the partially aromatic polyamide or may be adry blend of the thermoplastic polyester and a masterbatch containingthe partially aromatic polyamide.

The mixing ratio of the above thermoplastic polyester and the partiallyaromatic polyamide constituting the polyester composition of theinvention is 0.01 to 50 parts by weight, preferably 0.01 to 30 parts byweight of the partially aromatic polyamide per 100 parts by weight ofthe thermoplastic polyester. In the case that a polyester compositionhaving a very little AA content and excellent in flavor retention isdesired to obtain from the above polyester composition, the addingamount of the partially aromatic polyamide is desirably 0.01 part byweight or more, further preferably 0.1 part by weight or more,particularly preferably 0.5 part by weight or more and preferably lessthan 5 parts by weight, more preferably less than 2 parts by weight,further preferably less than 1 part by weight per 100 parts by weight ofthe thermoplastic polyester.

Further, in the case that a polyester composition extremely excellent ingas barrier properties, having transparency not impairing practicality,having a very little AA content, and excellent in flavor retention isdesired to obtain from the above polyester composition, the addingamount is preferably 2 parts by weight or more, further preferably 3parts by weight or more, particularly preferably 5 parts by weight ormore and preferably 30 parts by weight or less, more preferably 25 partsby weight or less, further preferably 20 parts by weight or less per 100parts by weight of the thermoplastic polyester.

When the mixing amount of the partially aromatic polyamide is less than0.01 part by weight per 100 parts by weight of the thermoplasticpolyester, the AA content of the resulting polyester composition is notreduced and flavor retention of contents of the polyester compositionbecomes very bad in some cases, so that the amount is not preferable.Further, when the mixing amount of the partially aromatic polyamideexceeds 30 parts by weight per 100 parts by weight of the thermoplasticpolyester, transparency of the resulting polyester molded articlebecomes very bad and mechanical properties of the polyester packagingmaterial decreases in some cases, so that the amount is not preferable.

Furthermore, a melt mixture of the thermoplastic polyester and thepartially aromatic polyamide can be used as a masterbatch for mixingwith the thermoplastic polyester. In the case of the use as themasterbatch, the ratio is preferably 3 to 50 parts by weight of thepartially aromatic polyamide per 100 parts by weight of thethermoplastic polyester.

The polyester composition of the invention is characterized in that thecontent of an alkali metal atom in the polyester composition is withinthe range of 0.1 to 300 ppm.

The lower limit of the content of an alkali metal atom in the polyestercomposition is preferably 1 ppm, more preferably 5 ppm. Further, theupper limit of the content of an alkali metal atom in the polyestercomposition is preferably 270 ppm, more preferably 250 ppm, furtherpreferably 200 ppm.

When the content of an alkali metal atom in the polyester composition isless than 0.1 ppm, at the production of molded articles using such apolyester composition, severe coloring may occur, burn lines andnon-melted matter are apt to generate, and as a result, appearance ofthe polyester molded article becomes bad. On the other hand, when thecontent of an alkali metal atom in the polyester composition is largerthan 300 ppm, burn lines and non-melted matter are hardly generated buttransparency and flavor retention of the resulting molded articlebecomes bad, decrease in molecular weight occurs, and mechanicalstrength may decrease.

As a method for making the content of an alkali metal atom in thepolyester composition within the range of 0.1 to 300 ppm, use can bemade of a method of regulating the content of an alkali metal atomcontained in the partially aromatic polyamide according to the amount ofthe partially aromatic polyamide to be used, a method of regulating thecontent of an alkali metal atom contained in the polyester, or the likemethod.

The content of an alkali metal atom in the above partially aromaticpolyamide for use in the invention is determined by atomic absorptionspectrometry, emission spectrometry, inductively coupled plasma(hereinafter, abbreviated as ICP) emission spectrometry, ICP massspectrometry, fluorescent X-ray analysis, and the like, which can bechosen according to the concentration of the alkali metal atom.

Further, the polyester composition of the invention is characterized inthat the content of phosphorus atom in the polyester composition is from5 to 200 ppm.

The lower limit of the content of phosphorus atom in the polyestercomposition is preferably 6 ppm, more preferably 7 ppm, furtherpreferably 8 ppm. Further, the upper limit of the content of phosphorusatom in the polyester composition is preferably 180 ppm, more preferably160 ppm, further preferably 130 ppm.

When the content of phosphorus atom in the polyester composition is lessthan 5 ppm, at the production of a molded article using such a polyestercomposition, severe coloring may occur, burn lines and non-melted matterare apt to generate, and thermal degradation at molding occurs to alarge extent. On the other hand, when the content of the phosphorus atomin the polyester composition is larger than 200 ppm, thermal stabilityis excellent and generation of burn lines and non-melted matter arehardly observed but transparency and flavor retention of the resultingmolded article becomes bad in some cases.

As a method for making the content of phosphorus atom in the polyestercomposition within the range of 5 to 200 ppm, use can be made of amethod of regulating the content of phosphorus atom contained in thepartially aromatic polyamide according to the amount of the partiallyaromatic polyamide to be used, a method of regulating the content ofphosphorus atom contained in the polyester, or the like method.

It is preferable that the Color-L value of the molded article obtainedby injection molding of the polyester composition of the inventionaccording to the measuring method (8) to be described below is 80.0 ormore and the haze thereof is 20% or less. The Color-L value is morepreferably 82.0 or more, further preferably 84.0 or more. Furthermore,the haze is more preferably 15% or less, further preferably 10% or less.When the Color-L value of the resulting molded article is less than 80.0or the haze is more than 20%, not only transparency of the moldedarticle is bad but also the appearance looks darkly, so that the valueas a packaging material is poor in some cases.

When a polyester using an antimony catalyst is used as the polyestercomposition, as mentioned above, the antimony is reduced to precipitateas metal antimony by the action of phosphorus, which results in darklycolored appearance in some cases. Therefore, a desirable result can beachieved by regulating the content of antimony and the content ofphosphorus atom in the polyester composition.

Further, since the polyester has low compatibility with the partiallyaromatic polyamide, haze increases not only by the elevation of thecontent of the partially aromatic polyamide in the composition, the hazevalue increases but also by precipitation of metal antimony, cloudingwith excess phosphorus atom, a crystallization-accelerating effect by analkali metal, a crystallization-accelerating effect of a resin finepowder called fine, and the like. Therefore, haze can be reduced to 20%or less by regulating the adding amount of the partially aromaticpolyamide, the antimony content in the polyester composition, thecontent of phosphorus atom, the content of phosphorus atom, and thecontent of fine or the like. Further, a measure of enhancingcompatibility by copolymerization of the partially aromatic polyamidewith an aromatic dicarboxylic acid component or the like, a measure ofmaking the refractive index of the polyester close to that of thepartially aromatic polyamide, or the like measure are also effective.

It is preferred that the difference (A_(t)−A₀) between the acetaldehydecontent (A_(t)) (ppm) in the molded article obtained by injectionmolding of the polyester composition of the invention according to themethod described in the following method (5) and the acetaldehydecontent (A₀) (ppm) of the polyester composition before injection moldingis 20 ppm or less, preferably 15 ppm or less, further preferably 10 ppmor less, most preferably 5 ppn or less. When the difference (A_(t)−A₀)between the acetaldehyde contents before and after the injection moldingexceeds 20 ppm, flavor retention of the resulting polyester packagingmaterial becomes bad. Further, the lower limit of the difference(A_(t)−A₀) between the acetaldehyde contents before and after theinjection molding is 1 ppm. For reducing the difference less than thevalue, the production conditions of the polyester composition should beunproductive conditions and hence it is uneconomical.

The polyester composition having a difference (A_(t)−A₀) between theacetaldehyde content (A_(t)) after the injection molding and theacetaldehyde content (A₀) before the injection molding of 20 ppm or lesscan be obtained by using a thermoplastic polyester whose acetaldehydecontent is 5 ppm or less or a thermoplastic polyester whose acetaldehydecontent is 10 ppm or less and whose remaining polycondensation catalystis deactivated.

Further, the above polyester composition having a difference (A_(t)−A₀)of 20 ppm or less can be also obtained by bringing a polyestercomposition comprising the thermoplastic polyester having anacetaldehyde content of 10 ppm or less and the partially aromaticpolyamide with water, water vapor or a gas containing water vapor.

The acetaldehyde content in the polyester composition of the inventionis 20 ppm or less, preferably 15 ppm or less, further preferably 10 ppmor less. When the acetaldehyde content in the polyester composition ofthe invention exceeds 20 ppm, flavor retention of the polyestercomposition becomes bad. Further, the lower limit of the acetaldehydecontent in the polyester composition is 3 ppm and the reduction to lessthan the value is problematic since the molding therefor is molding withno thought of profit.

In the polyester composition of the invention, the increase (ΔAA) (ppm)of the acetaldehyde content during melting treatment at 290° C. for 30minutes is preferably 20 ppm or less, more preferably 15 ppm or less,further preferably 13 ppm or less. When the increase (ΔAA) (ppm) of theacetaldehyde content at the melting treatment exceeds 20 ppm, at moldingof the polyester composition using recycled reusable materials such asused PET bottles in part, it becomes very difficult to reduce the AAcontent in the resulting polyester composition and also it becomesnecessary to reduce extremely the mixing ratio of the recycled reusablematerials to a virgin PET resin.

In addition, the formaldehyde content (hereinafter, sometimesabbreviated as FA) in the polyester composition of the invention ispreferably 3 ppm or less, more preferably 2 ppm or less, furtherpreferably 1 ppm or less. When the formaldehyde content in the polyestercomposition of the invention exceeds 3 ppm, flavor retention of thepolyester composition becomes bad.

In the polyester composition of the invention, the content of a cyclictrimer derived from the polyester is preferably 0.7% by weight or less,more preferably 0.5% by weight or less.

For maintaining the content of the cyclic trimer derived from thethermoplastic polyester to 0.7% by weight or less, it is necessary tosuppress the content of the above cyclic trimer to preferably 0.50% byweight or less, more preferably 0.45% by weight or less, furtherpreferably 0.40% by weight or less. In the case that the polyestercomposition is thermally resistant blow-molded article, when the contentof the cyclic trimer in the polyester composition exceeds 0.70% byweight, attachment of oligomers derived from the polyester such as thecyclic trimer to the surface of a heated mold increases with time, sothat it takes a lot of effort to clean the mold and at the same timediscontinuation of the molding results in economic loss. The lower limitis 0.10% by weight and reduction to less than the value is problematicsince production conditions of the polyester with no thought of profitshould be adopted.

Further, in the polyester composition of the invention, the increase ofthe cyclic ester trimer (ΔCT₁) during melting treatment at 290° C. for30 minutes is preferably 0.40% by weight or less, more preferably 0.3%by weight or less.

For maintaining the increase of the above cyclic ester trimer (ΔCT₂)during melting treatment at 290° C. for 30 minutes to 0.40% by weight orless, it is necessary to use a thermoplastic polyester having anincrease of the cyclic ester trimer (ΔCT₁) during melting treatment at290° C. for 30 minutes of 0.40% by weight or less, preferably 0.35% byweight or less, further preferably 0.30% by weight or less. When athermoplastic polyester wherein the increase of the cyclic ester trimer(ΔCT₁) during melting treatment at 290° C. for 30 minutes exceeds 0.40%is used, the amount of the cyclic ester trimer increases at resinmelting during the molding of the polyester composition and attachmentof the oligomers to the surface of the heated mold rapidly increases,whereby transparency of the resulting blow-molded articles or the likebecomes extremely bad.

The thermoplastic polyester wherein the increase of the cyclic estertrimer (ΔCT₁) during melting treatment at 290° C. for 30 minutes is0.40% or less can be produced by deactivating the polycondensationcatalyst remaining in the thermoplastic polyester obtained after meltpolycondensation or after solid-phase polymerization. As a method fordeactivating the polycondensation catalyst in the thermoplasticpolyester, methods the same as those mentioned above can be employed.

In this connection, when the thermoplastic polyester is PET, the cyclicester trimer means a cyclic trimer comprising terephthalic acid andethylene glycol.

The content of the cyclic ester trimer-derived from the thermoplasticpolyester in the polyester composition of the invention is preferably0.50% by weight or less, more preferably 0.45% by weight or less,further preferably 0.40% by weight or less. When the content of thecyclic ester trimer derived from the thermoplastic polyester in thepolyester composition exceeds 0.50% by weight, attachment of theoligomers to the surface of the heated mold rapidly increases, wherebytransparency of the resulting blow-molded articles becomes extremely badand flavor retention becomes bad, so that the case is problematic.

The content of the cyclic amide monomer containing an m-xylylene groupin the polyester composition of the invention is 0.3% by weight or less,preferably 0.28% by weight or less, further preferably 0.25% by weightor less. When the content of the above cyclic amide monomer in thepolyester composition exceeds 0.3% by weight, flavor retention ofcontents filled in a polyester molded article becomes bad, so that thecase is problematic.

For achieving it, it is preferable that the content of the cyclic amidemonomer containing an m-xylylene group in the polyester composition ofthe invention is 0.3% by weight or less, preferably 0.28% by weight orless, further preferably 0.25% by weight or less.

When the content of the cyclic amide monomer exceeds 0.3% by weight,mold fouling becomes very severe which is formed by attaching foreignmatter to the inner surface of the mold during the molding of thepolyester composition having improved thermal resistance and the exhaustoutlet and exhaust pipe of gases of the mold. The lower limit of thecontent of the cyclic amide monomer is preferably 0.001 ppm for theeconomical reason and the like. The cyclic amide monomer can be measuredby a high-performance liquid chromatography to be described below.

The method for regulating the contents of the polyester composition andthe cyclic amide monomer in the polyester composition of the inventionis not particularly limited and, for example, it can be produced asfollows. Namely, according to the blending amount of the partiallyaromatic polyamide to the thermoplastic polyester, it is achieved byusing a partially aromatic polyamide having a reduced content of thecyclic amide monomer so that the contents of the polyester compositionand the cyclic amide monomer in the polyester composition satisfies thevalue defined in claims of the invention. Further, it is also achievedby treating the polyester composition obtained from the polyestercomposition containing the partially aromatic polyamide or the polyestercomposition obtained from the above polyester composition with water, anorganic solvent, or the like to extract and remove the above cycliccompound. The method for producing the partially aromatic polyamidehaving a reduced content of the above cyclic amide monomer is notlimited and there may be mentioned extraction with water or an organicsolvent, change of polycondensation conditions, thermal treatment underreduced pressure, and methods of combining these methods.

The intrinsic viscosity of the polyester composition of the invention isin the range of preferably 0.55 to 1.00 dl/g, more preferably 0.58 to0.95 dl/g, further preferably 0.60 to 0.90 dl/g.

Furthermore, the polyester composition may be a polyester compositioncomprising 100 parts by weight of a thermoplastic polyester, 0.01 to 100parts by weight of a partially aromatic polyamide, and 5×10⁻⁴ to 1 partby weight of an amino group-containing compound.

Examples of the amino group-containing compound include1,8-diaminonaphthalate, 3,4-diaminobenzoic acid, 2-aminobenzamide,biuret, malonamide, salicylamide, salicylanilide, o-phenylenediamine,o-mercaptobenzamide, N-acetylglycineamide, 3-mercapto-1,2-propanediol,4-amino-3-hydroxybenzoic acid, disodium4,5-dihydroxy-2,7-naphthalenedisulfonate salt, 2,3-diaminopyridine,2-aminobenzsulfonamide, 2-amino-2-methyl-1,3-propanediol,4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether,4,4′-diaminodiphenyl sulfone, 2,2-bis(4-aminophenyl)propane, melamine,benzoguanamine, propioguanamine, stearoguanamine, spiroguanamine,stearylamine, lauroylamine, eicosylamine, spiroacetal diamine,polyoxyethylenediamine, amino group-terminated polyethers, e.g.,aminoethyl etherified or aminopropyl etherified polyethylene glycoland/or polypropylene glycol, amino-terminated polyesters, e.g.,aminoethyl etherified or aminopropyl etherified polyethylene adipate orsebacate, amino-terminated polyurethanes, amino-terminated polyureas,amino group-containing acylic resins, e.g., copolymers of aminogroup-containing acrylates or methacrylates such as 2-aminoethylacrylate, 2-aminoethyl methacrylate, 3-aminoethyl acrylate, 3-aminoethylmethacrylate, N-(2-aminoethyl)aminoethyl methacrylate, andN-(2-aminoethyl)aminopropyl methacrylate with methyl acrylate, ethylacrylate, styrene, or the like, amino group-modified olefinic resins,e.g., polyethylene, polypropylene, and etylene-propylene copolymergraft-modified with amino group-containing acrylates or methacrylates,amino group-containing organopolysiloxanes, e.g., organopolysiloxanescontaining 3-aminoalkylsiloxane unit and an unit such asdimethylsiloxane, diphenylsiloxane, or methylphenylsiloxane, primaryamino group-containing melamine resins, primary amino group-containingguanamine resins, primary amino group-containing alkyd resins, e.g.,amino alcohol-modified alkyd resins, agmatine, alkyne, octopamine,D-octopine, cadaverine, cystamine, cysteamine, spermidine, tyramine,spermine, tributamine, noradrenaline, histamine, bithiamine,hydroxytyramine, 5-hydroxytributamine, hypotaurine, azeserine,L-asparamine, L-aspartic acid, L-α-aminobutyric acid, L-arginine,L-alloisoleucine, L-allothreonine, L-isoleucine, L-ethionine,L-ornithine, L-canavanine, L-carboxymethylcystein, L-kynurenine,glycine, L-glutamine, L-glutamic acid, creatinine, L-cystathionine,L-cysteine, L-cysteic acid, L-cystine, L-citrulline,3,4-dihydroxyphenylalanine, L-3,5-diiodotyrosine, L-serine, L-tyroxine,L-tyrosine, L-tryptophan, L-threonine, norvaline, norleucine, L-valine,L-histidine, L-hydroxyproline, L-hydroxylysine, L-phenylalanine,L-α-phenylglycine, L-homoserine, L-methionine, L-1-methylhistidine,L-lanthionine, L-lysine, L-leucine, actinomycin C1, apamin, eledoisin,oxytocin, gastrin II, L-carnosine, L-glutathione,L-γ-glutamyl-L-cysteine, L-cysteinylglycine, vasopressin,α-melanotropin, insulin, α-chymotrypsin, glucagon, clupeine,corticotropin, subtilisin, secretin, cytochrome C, tyrocalcitonin,trypsin, papain, histone, ferredoxin, proinsulin, pepsin, hemoglobin,myoglobin, lactalbumin, and lysozyme.

As the polyester and the partially aromatic polyamide, those mentionedabove can be used and also as the polyester composition, those mentionedabove are preferable except that an amino group-containing compound isadded.

The mixing amount of the amino group-containing compound is preferably5×10⁻³ or more, further preferably 1×10⁻² or more per 100 parts byweight of the polyester.

In the case of less than 5×10⁻⁴, the AA content of the resulting moldedarticle is not reduced and flavor retention of contents of the moldedarticle becomes extremely bad in some case. Further, when the amountexceeds 1 part by weight, the resulting molded article is colored acolor characteristic to the amino group-containing compound and is poorin practicality in some case.

Into the polyester composition of the invention, there may be blended,if necessary, other various additives such as a UV absorbent, anantioxidant, an oxygen absorbent, an oxygen trapping agent, a lubricantto be added externally or a lubricant precipitated internally duringreaction, a releasing agent, a nucleic agent, a stabilizer, anantistatic agent, a dye, and a pigment which are known. Further, it isalso possible to add a UV shielding resin, a thermally resistant resin,a recycled article from used polyethylene terephthalate bottles, and thelike, in appropriate ratios.

Furthermore, in the case that the polyester composition of the inventionis a film, in order to improve handling properties such as slidingproperties, winding properties, and blocking resistance, it is possibleto blend inorganic particles of calcium carbonate, magnesium carbonate,barium carbonate, calcium sulfate, barium sulfate, lithium phosphate,calcium phosphate, magnesium phosphate, or the like, organic saltparticles of calcium oxalate or a terephthalate salt of calcium, barium,zinc, manganese, magnesium, or the like, or inert particles such asparticles of crosslinked polymers, e.g., homopolymers or copolymers ofvinyl monomers such as divinylbenzene, styrene, acrylic acid,methacrylic acid, acrylic acid, or methacrylic acid.

Further, in order to accelerate crystallization, to acceleratecrystallization rate at a mouth part at production of biaxially orientedblow molded bottles, and to stabilize it, the polyester composition maycontain a polyolefin, a polyamide other than the partially aromaticpolyamide, a polyoxymethylene, polybutylene terephthalate, or the likein an amount of 0.1 ppb to 1000 ppm. The lower limit of the content ofthese resin is preferably 0.5 ppb, more preferably 1 ppb and the upperlimit is preferably 100 ppm, further preferably 1 ppm, particularlypreferably 100 ppb.

The method for adding them has been described in detail in JP2002-249573 A and so on, which are incorporated herein by reference.

The polyester composition of the invention can be obtained according toknown production processes.

The following will describe a simple process for producing variouspolyester compositions in the case that the thermoplastic polyester ispolyethylene terephthalate (PET) as a representative example.

The polyester composition of the invention can be obtained by mixing theabove thermoplastic polyester with the above polyamide according tohitherto known methods. For example, there may be mentioned acomposition obtained by dry-blending the above polyamide chips with thethermoplastic polyester chips in a tumbler, a V-type blender, Henschelmixer, or the like, a composition obtained by further melt-mixing of thedry-blended mixture-in a single-screw extruder, twin-screw extruder, akneader, or the like one or more times, a composition obtained byfurther solid-phase polymerization of the melted mixture under highvacuum or under an inert gas atmosphere, and the like composition.

Furthermore, the above polyamide may be used after pulverization. Inparticular, the pulverization is advantageous in the case of acomposition where the above polyamide is used in a small amount. Theparticle size when pulverized is preferably about 10 mesh or less.Further, there may be mentioned a method of attaching a solutionobtained by dissolving the polyamide in a solvent such ashexafluoroisopropanol, a method of bringing the above thermoplasticpolyester into collision and contact with a member made of the abovepolyamide in a space where the above member is present to attach theabove polyamide onto the surface of the above thermoplastic polyesterchips, and the like method.

In the case that the polyester composition of the invention is asheet-like article, it can be produced using a general sheet-moldingmachine equipped with an extruder and die, for example.

Further, the sheet-like article can be also molded into a cup-likearticle or a tray-like article by pneumatic molding or vacuum molding.In addition, the polyester composition of the invention-can be also usedin the application of tray-like containers for cooking foods in amicrowave range and/or an oven range or heating frozen foods. In thiscase, after the sheet-like article is molded into a tray shape, it isthermally crystallized to improve thermal resistance thereof.

In the case that the polyester composition of the invention is anoriented film, the sheet-like article obtained by injection molding orextrusion molding is molded using any orientation method among uniaxialorientation, successive biaxial orientation, and simultaneous biaxialorientation.

For the production of the oriented film, the orientation temperature isusually from 80 to 130° C. The orientation may be uniaxial or biaxial,but preferred is biaxial from a viewpoint of film practical properties.The orientation magnification is in the range of usually 1.1 to 10times, preferably 1.5 to 8 times in the case of uniaxial orientation andis in the range of usually 1.1 to 8 times, preferably 1.5 to 8 timesboth in a longitudinal direction and in a transverse direction in thecase of biaxial orientation. Further, the ratio of magnification in alongitudinal direction/magnification in a transverse direction isusually from 0.5 to 2, preferably from 0.7 to 1.3. The resultingoriented film can be also further thermally fixed to improve thermalstability and mechanical strength. The thermal fixing is carried outunder tension at 120° C. to 240° C., preferably from 150° C. to 230° C.,usually for several seconds to several hours, preferably for severaltens of seconds to several minutes.

For the production of blow-molded articles, a preform obtained bymolding the PET composition of the invention is subjected to orientationblow molding and an apparatus used in conventional blow molding of PETcan be employed. Specifically, for example, a preform is once formed byinjection molding or extrusion molding and directly or after processingof the mouth part and bottom part, it is reheated and subjected tobiaxial orientation blow molding such as a hot parison method or a coldparison method. The molding temperature in this case, specificallytemperatures at each part of the cylinder and the nozzle part of amolding machine are usually in the range of 260 to 310° C. Theorientation temperature is usually from 70 to 120° C., preferably from90 to 110° C. and the orientation magnification may be usually in therange of 1.5 to 3.5 in the longitudinal direction and in the range of 2to 5 times in the circumferential direction. The resulting blow-moldedarticles can be used as they are but in the case that drinks requiringfilling while hot, such as fruit juice drinks and oolong tea, they aregenerally used after further thermal fixing treatment in the blow moldto impart thermal resistance. The thermal fixing is usually carried outunder tension such as pneumatic one at 100° C. to 200° C., preferablyfrom 120° C. to 180° C. for several seconds to several hours, preferablyfor several seconds to several minutes.

Further, in order to impart thermal resistance to the mouth part, themouth part of the preform obtained by injection molding or extrusionmolding is crystallized in an oven equipped with a far-infrared ornear-infrared heater or the mouth part after bottle molding iscrystallized by the above heater.

Furthermore, the polyester composition of the invention may be oneconstituting layer of a laminated molded article, a laminated film, orthe like. In particular, it is used as containers and the like in thelaminated form with PET. Examples of the laminated molded articleinclude a molded article of a two-layer structure composed of two layersof an outer layer comprising the polyester composition of the inventionand an inner PET layer or of a two-layer structure composed of twolayers of an inner layer comprising the polyester composition of theinvention and an outer PET layer, a molded article of a three-layerstructure composed of an intermediate layer comprising the polyestercomposition of the invention and outer and innermost layers of PET or ofa three-layer structure composed of outer and innermost layerscomprising the polyester composition of the invention and anintermediate PET layer, a molded article of a five-layer structurecomposed of intermediate layers comprising the polyester composition ofthe invention and innermost, central, and innermost layers of PET, andthe like molded article. In the PET layer, the other gas barrier resin,a UW shielding resin, a heat-resistant resin, recycled articles fromused polyethylene terephthalate bottles, and the like can be mixed andused in appropriate ratios.

In addition, examples of other laminated molded article includelaminated molded articles with resins other than the thermoplasticpolyester, such as polyolefins, and laminated molded articles withheterogeneous basal materials such as paper and metal plates.

The thickness of the above laminated molded article and the thickness ofeach layer are not particularly limited. Further, the above laminatedmolded article can be used as various shapes such as sheet-likearticles, film-like articles, plate-like articles, blow-molded articles,and containers.

The production of the above laminated article can be carried out byco-extrusion using extruders and multilayer multi-kind dies whose numbercorresponds to the kinds of the resin layers or by co-injection usinginjectors and co-injection runners whose number corresponds to the kindsof the resin layers.

The polyester composition of the invention may be a film which is usedto laminate one side or both sides of a metal plate to be laminated. Asthe metal plate to be used, there may be mentioned tin plate, tin-freesteel, aluminum, and the like.

As lamination methods, conventionally known methods can be applied andare not particularly limited but it is preferable to carry out a thermallamination method capable of achieving organic solvent-free laminationand thus avoiding adverse effects on taste and smell of foods due toresidual solvents. In particular, a thermal lamination method byenergization processing of a metal plate is particularly recommended.Further, in the case of double-sided lamination, the lamination may becarried out simultaneously or successively.

In this connection, needless to say, the film can be laminated to themetal plate using an adhesive.

Further, a metal container is obtained by molding using the abovelaminated metal plate. The molding methods for the above metalcontainers are not particularly limited. Furthermore, the shape of themetal container is also not particularly limited but it is preferable toapply to so-called two-piece can which is manufactured by forming suchas drawing forming, draw-ironing forming, and stretch draw forming.However, it is also possible to apply to so-called three-piece cansuitable for filling foods such as retort foods and coffee drinks, intowhich contents are filled by winding up top and bottom caps.

Incidentally, the following will describe measuring methods of maincharacteristic values in the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The following will explain the invention more specifically withreference to Examples but the invention is not limited to theseExamples. The following will describe measuring methods of maincharacteristic values in the present specification.

(Evaluation Methods)

(1) Intrinsic Viscosity (IV)

It was determined based on a solution viscosity at 30° C. in a mixedsolvent of 1,1,2,2-tetrachloroethane/phenol (weight ratio of 2:3) (theunit is dl/g).

(2) Diethylene Glycol Content Copolymerized in Polyester (Hereinafter,Referred to as “DEG Content”)

A polyester was decomposed by methanol and an amount of DEG wasdetermined quantitatively, the content being indicated by a ratio tototal glycol components (mol %).

(3) Content of Cyclic Ester Trimer (Hereinafter, Referred to as “CTContent”) (% by Weight)

Three hundred milligrams of a sample was dissolved in 3 ml of a mixedsolution of hexafluoroisopropanol/chloroform (volume ratio of 2/3) andthe resulting solution was further diluted by adding 30 ml ofchloroform. Thereto was added 15 ml of methanol to precipitate apolymer, followed by filtration. The filtrate was evaporated to drynessand the residue was diluted with 10 ml of dimethylformamide, a cyclicester trimer being determined quantitatively by high performance liquidchromatography.

(4) Acetaldehyde Content (Hereinafter Referred to as “AA Content”) (ppm)

After a sample/distilled water=1 g/2 cc was placed in a glass ampoule,inside of which had been substituted with nitrogen, the upper part ofthe ampoule was melt-sealed under a nitrogen seal and extractiontreatment was conducted at 160° C. for 2 hours. After cooling,acetaldehyde in the extract solution was measured by highly sensitivegas chromatography, the concentration being indicated by ppm.

(5) Formaldehyde Content (Hereinafter Referred to as “FA Content”) (ppm)

After a sample/distilled water=6 g/12 cc was placed in a glass ampoule,inside of which had been substituted with nitrogen, the upper part ofthe ampoule was melt-sealed under a nitrogen seal and extractiontreatment was conducted at 160° C. for 2 hours, followed by cooling.Thereafter, formaldehyde in the extract solution was derivatized withdinitrophenylhydrazine, followed by measurement by highly sensitive gaschromatography. The concentration was indicated by ppm.

(6) Difference between Acetaldehyde Contents before and after InjectionMolding (Hereinafter Referred to as “A_(t)−A₀”)

A molded plate with steps was injection-molded according to the methodto be described in the following (17) and a sample was taken out of theplate having a thickness of 2 mm (A part in FIG. 1). The content ofacetaldehyde (A_(t)) was determined according to the measuring method of(4) and then the difference between the acetaldehyde contents before andafter injection molding was determined according to the followingequation.

Difference between the acetaldehyde contents before and after injectionmolding (A_(t)−A₀) (ppm)=Acetaldehyde content in a molded plate withsteps after injection molding (A_(t)) (ppm)−Acetaldehyde content in adry polyester composition before injection molding (A₀) (ppm)

(7) Increase of Acetaldehyde Content During Melt Treatment of PolyesterComposition (Hereinafter Referred to as “ΔAA”)

Three grams of a sample having a size of about 1 to 3 mm square wastaken out of a polyester composition. The sample was placed in a testtube made of glass and vacuum-dried at about 50 to 70° C. and then itwas immersed in an oil bath at 290° C. for 30 minutes to effect melttreatment. The increase of the acetaldehyde content during the melttreatment was determined according to the following equation.

The increase of the acetaldehyde content during melttreatment  (ppm) = Acetaldehyde  content  after  melt  treatment  (ppm) − Acetaldehyde  content  before  melt  treatment  but  after  dried  (ppm)(8) Increase of Cyclic Ester Trimer During Melt Treatment of Polyester(Hereinafter Referred to as “ΔCT₁ Amount”) (% by Weight) and Increase ofCyclic Ester Trimer During Melt Treatment of Polyester Composition(Hereinafter Referred to as “ΔCT₂ Amount”) (% by Weight)

Three grams of dried polyester chips or a polyester composition wasplaced in a test tube made of glass and immersed in an oil bath at 290°C. for 30 minutes to effect melt treatment. The polyester compositionwas cut into a size of about 1 to 3 mm square and then subjected tomeasurement.

The increase of a cyclic ester trimer during melt treatment of polyester(ΔCT₁ amount) and the increase of a cyclic ester trimer during melttreatment of a polyester composition (ΔCT₂ amount) was determinedaccording to the following equation.Increase  of  cyclic  ester  trimer  during  melt  treatment  (%  by  weight) = Content  of  cyclic  ester  trimer  after  melt  treatment  (%  by  weight) − Content  of  cyclic  ester  trimer  before  melt  treatment  (%  by  weight)(9) Content of Cyclic Amide Monomer in m-xylylene Group-ContainingPolyamide and Polyester Packaging Material (hereinafter Referred to as“CM Content”) (% by Weight)

One hundred milligrams of a sample was dissolved in 3 ml of a mixedsolution of hexafluoroisopropanol/chloroform (volume ratio of 2/3) andthen diluted by adding 20 ml of chloroform, followed by addition of 10ml of methanol. The solution was concentrated on an evaporator and theresidue was re-dissolved in 20 ml of dimethylformamide. Aftercentrifugation and filtration, the content was quantitatively determinedby high-performance liquid chromatography.

(10) Relative Viscosity of m-xylylene Group-Containing Polyamide(Hereinafter Referred to as “Rv”)

A sample (0.25 g) was dissolved in 25 ml of 96% sulfuric acid and 10 mlof the solution was measured at 20° C. in an Ostwalt viscometer tube,the viscosity being determined according to the following equation.Rv=t/t₀

-   -   t₀: number of seconds necessary to drop solvent    -   t: number of seconds necessary to drop sample solution        (11) Content of Sodium Atom in m-xylylene Group-Containing        Polyamide, Polyester Composition, and Polyester Composition        (Hereinafter Referred to as “Na Content”)

A sample was subjected to ashing decomposition in a platinum crucibleand 6 mol/L hydrochloric acid was added thereto, followed by evaporationto dryness. The residue was dissolved with 1.2 mol/L hydrochloric acidand the content was quantitatively determined by atomic absorptionanalysis.

(12) Content of Phosphorus Atom (ppm) (Hereinafter, the Content ofPhosphorus Atom in a Polyester Composition was Referred to as “X” andthe Content of Phosphorus Atom in a Polyester Packaging Material wasReferred to as “Y”)

A sample was subjected to dry decomposition to ash in the presence ofsodium carbonate or subjected to wet decomposition in a sulfuricacid-nitric acid-perchloric acid system or in a sulfuric acid-hydrogenperoxide solution system to convert phosphorus into orthophosphoricacid. Then, it was reacted with a molybdate salt in a 1 mol/L sulfuricacid solution to form phosphomolybdic acid, which was reduced withhydrazine sulfate. The absorbance of the resulting heteropoly blue at830 nm was measured by an absorptiometer (Shimadzu UV-150-02) to effectcalorimetric quantitative determination.

(13) Quantitative Determination of Remaining Antimony Atom in Polyester(ppm)

After polyester chips were subjected to melt treatment at 300° C.,antimony atom was quantitatively determined by fluorescent X-ray method.

(14) Measurement of Content of Fine

About 0.5 kg of a resin was placed on a sieve (diameter of 30 cm) wiredwith wire gauze having a nominal size of 1.7 mm in accordance withJIS-Z8801 and sieved at 1800 rpm for 1 minute by means of an oscillatingsieve shaker SNF-7 manufactured by Teraoka. This operation was repeatedto sieve 20 kg of the resin in total.

The fine sieved out under the sieve was washed with ion-exchange waterand collected by filtration through G1 glass filter manufactured byIwaki Glass. After they were dried at 100° C. for 2 hours together withthe glass filter, they were cooled and weighed. The same operations ofwashing with ion-exchange water and drying were repeated and it wasconfirmed to reach a constant weight. The weight of the fine wasdetermined by subtracting the weight of the glass filter from theconstant weight. The content of the fine was a quotient of the weight ofthe fine/the weight of total resin sieved.

(15) Evaluation of Mold Fouling

A predetermined amount of thermoplastic polyester chips dried in a dryerusing nitrogen gas and a predetermined amount of m-xylylenegroup-containing polyamide chips dried in a dryer using nitrogen gaswere dry-blended. Using the blend, a preform was obtained by molding ata resin temperature of 285° C. by means of an injection-molding machineM-150C (DM) manufactured by Meiki Co., Ltd. After the mouth part of thepreform was thermally crystallized by means of a mouth-partcrystallizing apparatus made by us, the resulting preform was subjectedto biaxial orientation blow molding using a orientation blow moldingmachine LB-01E manufactured by Corpoplast and subsequently thermallyfixed in the mold set at about 145° C. to obtain a 1000 cc blow-moldedarticle. Under the same conditions, 2000 pieces of the blow-moldedarticles were continuously obtained by the orientation blow molding andthe surface states of the mold before and after the molding was visuallyobserved and evaluated as follows.

AA: No change is observed before and after continuous molding test

A: Slight attached matter is observed after continuous molding test

B: Considerable attached matter is observed after continuous moldingtest

C: Extremely much attached matter is observed after continuous moldingtest

(16) Color Tone (Color-L Value)

A sample was cut out of the molded article (thickness of 2 mms) in thefollowing (17) and measured by means of a color-difference meter TC-1500MC88-type manufactured by Tokyo Denshoku Co., Ltd. Color-L valueindicates white color when the value is close to 100 and also indicatesgray to black when the value-is close to 0. Further, at the measurement,the apparatus was sufficiently stabilized beforehand by being allowed tostand for 1 hour or more after power-on. (17) Molding of Molded Platewith Steps

In the molding of the molded plate with steps, polyester and m-xylylenegroup-containing polyamide chips dried under reduced pressure at 140° C.for about 16 hours using a vacuum drier was subjected to injectionmolding by means of an injection molding machine M-150C (DM)manufactured by Meiki Co., Ltd. to form a molded plate with steps havinga gate part (G) as shown in FIGS. 1 and 2 and a thickness of 2 mm to 11mm (thickness of A part=2 mm, thickness of B part=3 mm, thickness of Cpart=4 mm, thickness of D part=5 mm, thickness of E part=10 mm,thickness of F part=11 mm).

Polyester and m-xylylene group-containing polyamide chips dried underreduced pressure using a vacuum drier DP61-type manufactured by YamatoScientific Co., Ltd. was used and the inside of a hopper for moldingmaterials was purged with a dry inert gas (nitrogen gas) in order toprevent moisture absorption during the molding. The plasticizingconditions by the injection molding machine M-150C-DM were as follows:Rotation number of feed screw=70%, rotation number of screw=120 rpm,Back pressure 0.5 MPa, and cylinder temperature was set at 45° C., 250°C., in order form just below the hopper, and 290° C. at following partsincluding nozzle. As injection conditions, injection pressure and dwellpressure were regulated so that injection speed and dwell pressure speedwere 20% and the weight of molded article was 146±0.2 g. At that time,the dwell pressure was regulated to a pressure 0.5 MPa lower than theinjection pressure.

The upper limits of the injection time and dwell pressure time were setat 10 seconds and 7 seconds, respectively, and the cooling time was setat 50 seconds, the whole cycle time including the molded article-takeofftime being about 75 seconds.

The temperature of the mold was controlled by introducing a coolingwater having a temperature of 10° C., the mold surface temperature atstable molding being about 22° C.

A test plate for evaluating characteristics of molded articles wereoptionally selected from molded articles obtained at 11th to 18th shotfrom the start of molding after introduction of molding material andresin substitution.

The plate having a thickness of 2 mm (A part in FIG. 1) was used formeasurement of crystallization temperature (Tc1) during temperatureelevation and-the plate having a thickness of 5 mm (D part in FIG. 1)was used for haze (haze %) measurement.

(18) Transparency of Blow-Molded Article

a) Non-heat resistant blow-molded article: An appearance of ablow-molded article molded according to the method described in Example1 was visually observed and evaluated according to the followingevaluation standards.

b) Heat resistant blow-molded article: An appearance of a blow-moldedarticle obtained after the molding in (15) was visually observed andevaluated according to the following evaluation standards. Transparencyfor a short time was evaluated after 10 pieces molding and transparencyafter continuous molding was evaluated after 2000 pieces molding.

(Evaluation Standards)

AA: Transparent

A: Transparent within a practical range and no observation of foreignmatter such as non-melted matter

B: Transparent within a practical range but observation of foreignmatter such as non-melted matter

C: Poor transparency, observation of coloring, or observation ofnon-melted matter

(19) Sensory Test

a) Non-heat resistant blow-molded article: After cooling of boileddistilled water to 50° C., it was placed in a blow-molded article andretained for 30 minutes after hermetically sealed. Thereafter, the wholewas allowed to stand at 50° C. for 10 days and, after opened, a test ontaste, smell, and the like was carried out. As a blank for comparison,distilled water was used. The sensory test was carried out by 10panelists according to the following standards and comparison wasconducted with average values.

b) Heat resistant blow-molded article: Boiled distilled water was placedin a blow-molded article and retained for 30 minutes after hermeticallysealed. Thereafter, the whole was allowed to stand at 50° C. for 5 daysand, after opened, a test on taste, smell, and the like was carried outin a similar manner to the above.

(Evaluation Standards)

AA: No strange taste and smell are felt.

A: Slight difference from blank is felt.

B: Difference from blank is felt.

C: Considerable difference from blank is felt.

CC: Very large difference from blank is felt.

(20) Oxygen Permeability (cc/One Container·24 hr·atm)

It was measured at 20° C. and 0% RH as a permeability per one 1000 ccbottle by means of an oxygen permeability measuring apparatus OX-TRAN100 manufactured by Modern Controls.

(21) Yellowing Degree of Blow-Molded Article

An appearance of the blow-molded article obtained after 3000 piecesmolding in (15) was visually observed and evaluated according to thefollowing.

AA: No coloring is observed.

A: Coloring is observed but is within a practical range.

C: Coloring is severe and practicality is poor.

(Polyethylene Terephthalate (PET))

Table 1 shows characteristics of PET's (1A) to (1E) and (2A) to (2E)used for evaluation tests of blow-molded articles. These PET's are thoseobtained by polymerization in a continuous melt polycondensation-solidphase polymerization apparatus using a Ge-based catalyst. Further, (2A)and (2B) are those treated in ion-exchange water at 90° C. for 5 hoursafter solid-phase polymerization. In this connection, the DEG contentsof these PET's were about 2.8 mol %.

Table 1 also shows characteristics of PET's (3A), (3B), and (3C) usingantimony as a catalyst, the DEG contents being all about 2.7 mol %. AllPET's (3A) and (3B) are those obtained by polymerization in a continuousmelt polycondensation-solid phase polymerization. apparatus and PET (3C)is a melt-polycondensed PET obtained in a continuous meltpolycondensation apparatus, whose IV is increased in a batch-typesolid-phase polymerization apparatus. TABLE 1 Characteristics ofPolyesters ΔCT₁ CT content amount Phosphorus Fine Remaining Sb IV AAcontent (% by (% by content content content (dl/g) (ppm) weight) weight)(ppm) (ppm) (ppm) PET(1A) 0.74 2.6 0.30 0.06 55 50 0 (Ge catalyst)PET(1B) 0.74 2.9 0.31 0.13 55 65 0 (Ge catalyst) PET(1C) 0.75 2.8 0.510.52 55 65 0 (Ge catalyst) PET(1D) 0.75 9.3 0.61 0.50 0 ca. 500 0 (Gecatalyst) PET(1E) 0.75 2.8 0.65 0.50 55 ca. 500 0 (Ge catalyst) PET(2A)0.74 2.7 0.30 0.04 30 50 0 (Ge catalyst) PET(2B) 0.74 2.9 0.33 0.10 3050 0 (Ge catalyst) PET(2C) 0.75 3.0 0.53 0.50 34 60 0 (Ge catalyst)PET(2D) 0.75 8.0 0.60 0.50 0 ca. 500 0 (Ge catalyst) PET(2E) 0.75 3.00.65 0.53 50 ca. 500 0 (Ge catalyst) PET(3A) 0.78 3.0 0.32 Not 30 80 180measured PET(3B) 0.78 3.2 0.32 Not 30 80 230 measured PET(3C) 0.79 3.20.33 Not 30 5000 160 measured(m-Xylylene Group-Containing Polyamide (Ny-MXD6))

Table 2 shows characteristics of Ny-MIXD6 (1F) to (1I), (2F) to (2I),(3D), and (3E) used.

The Ny-MXD6 (1F) to (1I), (2F) to (2I), (3D), and (3E) are thoseobtained by a batch-type process of polycondensation by heatingm-xylylenediamine and adipic acid in the presence of NaOH or NaH₂PO₂·H₂Ounder pressure and under normal pressure in a pressure pot forpolycondensation. The sodium contents of the Ny-MXD6 (1F) to (1H) and(2F) to (2H) were set so that total amount of sodium atom in sodiumhypophosphite and sodium hydroxide was from 3.0 to 3.5 molar equivalentsto that of phosphorus atom. In this connection, the characteristics werevaried by changing the use ratio of m-xylylenediamine to adipic acid andthe polymerization conditions.

Ny-MXD6 (1I) and (2I) are those obtained in a similar manner to Ny-MXD6(1H). However, no phosphorus atom-containing compound and no alkalinecompound were added. TABLE 2 Characteristics of polyamides phosphorus Nacontent CM content AEG CEG Rv content (ppm) (ppm) (% by weight) (μmol/g)(μmol/g) AEG/CEG NyMXD6(1F) 1.80 290 650 0.48 185 35 5.3 NyMXD6(1G) 1.9555 120 0.59 86 70 1.2 NyMXD6(1H) 2.20 675 1500 1.50 73 70 1.0 NyMXD6(1I)2.30 0 0 1.20 50 75 0.7 NyMXD6(2F) 1.85 180 400 0.45 156 80 2.0NyMXD6(2G) 1.87 350 780 0.56 140 98 1.4 NyMXD6(2H) 2.20 750 1900 1.70 8063 1.3 NyMXD6(2I) 2.20 0 0 1.60 77 65 1.2 NyMXD6(3D) 1.30 210 400 0.45190 157 1.2 NyMXD6(3E) 1.80 150 300 0.60 155 75 2.1

EXAMPLE 1

Using 2 parts by weight of Ny-MXD6 (1G) per 100 parts by weight of PET(1C), they were dry-blended after separately dried by the drying methoddescribed in the evaluation method (15) and the blend was molded at aresin temperature of 285° C. by means of an injection molding machineM-150C (DM) manufactured by Meiki Co., Ltd to produce a preform. Thepreform was subjected to biaxial orientation blow molding using anorientation blow molding machine LB-01E manufactured by Corpoplast toobtain a 2000 cc blow-molded article.

Table 3 shows evaluation results of characteristics of the resultingblow-molded article.

It was possible to obtain a blow-molded article excellent intransparency and flavor retention wherein the sodium content of thepolyester composition was 2 ppm, the difference (A_(t)−A₀) between theacetaldehyde contents before and after injection molding was 8 ppm, theAA content of the blow-molded article was 10 ppm, the FA content was 0.4ppm, evaluation in sensory test was “AA”, and transparency was “AA”.

EXAMPLE 2

Using 10 parts by weight of Ny-MXD6 (1F) per 100 parts by weight of PET(1C), a 2000 cc blow-molded article was obtained by molding in a similarmanner to Example 1 and was evaluated.

Table 3 shows evaluation results of characteristics of the resultingblow-molded article.

The sodium content of the polyester composition was 59 ppm, thedifference (A_(t)−A₀) between the acetaldehyde contents before and afterinjection molding was 6 ppm, the AA content of the blow-molded articlewas 8 ppm, the FA content was 0.2 ppm, evaluation in sensory test was“A”, and transparency was “AA”, and thus there was no problem. Inaddition, oxygen barrier properties were also improved.

EXAMPLE 3

Using 30 parts by weight of Ny-MXD6 (1F) per 100 parts by weight of PET(1C), a blow-molded article was obtained by molding in a similar mannerto Example 1 and was evaluated.

Table 3 shows evaluation results of characteristics of the resultingblow-molded article.

The sodium content of the polyester composition was 150 ppm, thedifference (A_(t)−A₀) between the acetaldehyde contents before and afterinjection molding was 5 ppm, the AA content of the blow-molded articlewas 6 ppm, the FA content was 0.1 ppm, evaluation in sensory test was“A”, and transparency was “A”, and thus there was no problem.

COMPARATIVE EXAMPLE 1

Using 10 parts by weight of Ny-MXD6 (1I) per 100 parts by weight of PET(1D), a blow-molded article was obtained by molding in a similar mannerto Example 1 and was evaluated.

Table 3 shows evaluation results of characteristics of the resultingblow-molded article.

The sodium content of the polyester composition was 0 ppm, thedifference (A_(t)−A₀) between the acetaldehyde contents before and afterinjection molding was 18 ppm, the AA content of the blow-molded articlewas 22 ppm, the FA content was 4.8 ppm, and transparency was “C (colorednon-melted matter is observed)” which was bad, so that the articlelacked in practicality.

COMPARATIVE EXAMPLE 2

Using 30 parts by weight of Ny-MXD6 (1H) per 100 parts by weight of PET(1E), a blow-molded article was obtained by molding in a similar mannerto Example 1 and was evaluated.

Table 3 shows evaluation results of characteristics of the resultingblow-molded article.

The sodium content of the polyester composition was 346 ppm, thedifference (A_(t)−A₀) between the acetaldehyde contents before and afterinjection molding was 11 ppm, the AA content of the blow-molded articlewas 15 ppm, and the FA content was 4.2 ppm, but transparency was “C(transparency is poor)” and evaluation in sensory test was “CC” whichwere bad, so that the article lacked in practicality.

COMPARATIVE EXAMPLE 3

Using 100 parts by weight of PET (1D), a blow-molded article wasobtained by molding in a similar manner to Example 1 and was evaluated.

Table 3 shows evaluation results of characteristics of the resultingblow-molded article.

EXAMPLE 4

Using 10 parts by weight of Ny-MXD6 (G) per 100 parts by weight of PET(1A), a blow-molded article was obtained by molding according to themethod of the evaluation method (15) and evaluation on mold fouling wasalso carried out.

Table 4 shows evaluation results of characteristics and mold fouling ofthe resulting blow-molded article.

The difference (A_(t)−A₀) between the acetaldehyde contents of thepolyester composition before and after injection molding was 5 ppm, thesodium content of the blow-molded article was 11 ppm, the AA content ofthe blow-molded article was 9 ppm, the ΔAA content was 10 ppm, the FAcontent was 0.3 ppm, the content of cyclic ester trimer was 0.32% byweight, the increase of the content of cyclic ester trimer (ΔCT₂ amount)was 0.04% by weight, the CM content was 530 ppm, evaluation in sensorytest was “A”, transparency was “A”, and no attached matter to the moldwas observed.

EXAMPLE 5

Using 20 parts by weight of Ny-MXD6 (1F) per 100 parts by weight of PET(1B), a blow-molded article was obtained by molding according to themethod of the evaluation method (15) and evaluation on mold fouling wasalso carried out.

Table 4 shows evaluation results of characteristics and mold fouling ofthe resulting blow-molded article.

The difference (A_(t)−A₀) between the acetaldehyde contents of thepolyester composition before and after injection molding was 5 ppm, thesodium content of the blow-molded article was 108 ppm, the AA content ofthe blow-molded article was 7 ppm, the ΔAA content was 10 ppm, the FAcontent was 0.1 ppm, the content of cyclic ester trimer was 0.34% byweight, the increase of the content of cyclic ester trimer (ΔCT₂ amount)was 0.09% by weight, the CM content was 1100 ppm, evaluation in sensorytest was “A”, transparency was “A”, and no attached matter to the moldwas observed.

EXAMPLE 6

Using 30 parts by weight of Ny-MXD6 (1F) per 100 parts by weight of PET(A), a blow-molded article was obtained by molding according to themethod of the evaluation method (15) and evaluation on mold fouling wasalso carried out. Table 4 shows evaluation results of characteristicsand mold fouling of the resulting blow-molded article.

The difference (A_(t)−A₀) between the acetaldehyde contents of thepolyester composition before and after injection molding was 4 ppm, thesodium content of the blow-molded article was 150 ppm, the AA content ofthe blow-molded article was 5 ppm, the ΔAA content was 8 ppm, the FAcontent was 0.1 ppm, the content of cyclic ester trimer was 0.31% byweight, the increase of the content of cyclic ester trimer (ΔCT₂ amount)was 0.05% by weight, the CM content was 1400 ppm, evaluation in sensorytest was “A”, transparency was “A”, and no attached matter to the moldwas observed.

COMPARATIVE EXAMPLE 4

Using 0.05 part by weight of Ny-MXD6 (1I) per 100 parts by weight of PET(1D), a blow-molded article was obtained by molding according to themethod of the evaluation method (15) and evaluation on mold fouling wasalso carried out.

Table 4 shows evaluation results of characteristics and mold fouling ofthe resulting blow-molded article.

The difference (A_(t)−A₀) between the acetaldehyde contents of thepolyester composition before and after injection molding was 27 ppm, thephosphorus content of the blow-molded article was 0 ppm, the AA contentof the blow-molded article was 41 ppm, the ΔAA content was 35 ppm, theFA content was 5.4 ppm, the content of cyclic ester trimer was 0.66% byweight, the increase of the content of cyclic ester trimer (ΔCT₂ amount)was 0.50% by weight, evaluation in sensory test was “CC”, andtransparency was “C” which were bad, and mold fouling was severe.

COMPARATIVE EXAMPLE 5

Using 30 parts by weight of Ny-MXD6 (1H) per 100 parts by weight of PET(1E), a blow-molded article was obtained by molding according to themethod of the evaluation method (15) and evaluation on mold fouling wasalso carried out.

Table 4 shows evaluation results of characteristics and mold fouling ofthe resulting blow-molded article.

The difference (A_(t)−A₀) between the acetaldehyde contents of thepolyester composition before and after injection molding was 7 ppm, thesodium content of the blow-molded article was 346 ppm, the AA content ofthe blow-molded article was 13 ppm, the ΔAA content was 18 ppm, the FAcontent was 4.3 ppm, the content of cyclic ester trimer was 0.71% byweight, the increase of the content of cyclic ester trimer (ΔCT₂ amount)was 0.52% by weight, the CM content was 3800 ppm, evaluation in sensorytest was “CC”, and transparency was “C” which were bad, and mold foulingwas severe. TABLE 3 Characteristics of polyester compositions andblow-molded articles Polyester composition Blow-molded article NY-MXD6Na Oxygen permeability PET (part by (part by content AA content FAcontent Trans- Sensory (cc/one container · weight) weight) (ppm)A_(t)-A₀ (ppm) (ppm) parency test 24 hr · atm) Example 1 (1C) 100 (1G) 22 8 10 0.2 AA AA — Example 2 (1C) 100 (1F) 10 59 6 8 0.4 A AA 0.30Example 3 (1C) 100 (1F) 30 150 5 6 0.1 A A 0.20 Comparative (1D) 100(1I) 10 0 18 22 4.8 C A 0.30 Example 1 Comparative (1E) 100 (1H) 30 34611 15 4.2 C CC 0.17 Example 2 Comparative (1D) 100 — — 0 32 47 6.5 AA CC0.58 Example 3

TABLE 4 Characteristics of blow-molded articles Characteristics of blowmold articles Oxygen CT permeability NY-MXD6 Na AA FA content ΔCT₂ CMSen- (cc/one Mold PET (part by (part content content ΔAA content (% by(% by content Trans- sory container · 24 foul- weight) by weight) (ppm)(ppm) (ppm) (ppm) weight) weight) (ppm) parency test hr · atm) ingExample 4 (1A) 100 (1G) 10 11 9 10 0.3 0.32 0.04 530 A A 0.31 AA Example5 (1B) 100 (1F) 20 108 7 10 0.1 0.34 0.09 1100 A A 0.20 AA Example 6(1A) 100 (1F) 30 150 5 8 0.1 0.31 0.05 1400 A A 0.17 AA Comparative (1D)100 (1I) 0.05 0 41 35 5.4 0.66 0.50 10 C CC 0.57 C Example 4 Comparative(1E) 100 (1H) 30 346 13 18 4.3 0.71 0.52 3800 C CC 0.17 C Example 5CT = cyclic ester trimerCM = cyclic amide monomer

EXAMPLE 7

Using 2 parts by weight of Ny-MXD6 (2F) per 100 parts by weight of PET(2C), they were dry-blended after separately dried by the drying methoddescribed in the evaluation method (15) and the blend was molded at aresin temperature of 285° C. by means of an injection molding machineM-150C (DM) manufactured by Meiki Co., Ltd to produce a preform. Thepreform was subjected to biaxial orientation blow molding using anorientation blow molding machine LB-01E manufactured by Corpoplast toobtain a 2000 cc blow-molded article.

Table 5 shows evaluation results of characteristics of the resultingblow-molded article.

It was possible to obtain a blow-molded article excellent intransparency and flavor retention wherein the phosphorus content of thepolyester composition was 36 ppm, the difference (A_(t)−A₀) between theacetaldehyde contents before and after injection molding was 9 ppm, theAA content of the blow-molded article was 10 ppm, the FA content was 0.4ppm, evaluation in sensory test was “AA”, and transparency was “AA”.

EXAMPLE 8

Using 10 parts by weight of Ny-MXD6 (2F) per 100 parts by weight of PET(2C), a 2000 cc blow-molded article was obtained by molding in a similarmanner to Example 7 and was evaluated.

Table 5 shows evaluation results of characteristics of the resultingblow-molded article.

The phosphorus content of the polyester composition was 47 ppm, thedifference (A_(t)−A₀) between the acetaldehyde contents before and afterinjection molding was 6 ppm, the AA content of the blow-molded articlewas 9 ppm, the FA content was 0.1 ppm, evaluation in sensory test was“A”, and transparency was “AA”, and thus there was no problem. Inaddition, oxygen barrier properties were also improved.

EXAMPLE 9

Using 30 parts by weight of Ny-MXD6 (2G) per 100 parts by weight of PET(2C), a blow-molded article was obtained by molding in a similar mannerto Example 1 and was evaluated.

Table 5 shows evaluation results of characteristics of the resultingblow-molded article.

The phosphorus content of the polyester composition was 107 ppm, thedifference (A_(t)−A₀) between the acetaldehyde contents before and afterinjection molding was 5 ppm, the AA content of the blow-molded articlewas 6 ppm, the FA content was 0.1 ppm, evaluation in sensory test was“A”, and transparency was “A”, and thus there was no problem.

COMPARATIVE EXAMPLE 6

Using 10 parts by weight of Ny-MXD6 (2I) per 100 parts by weight of PET(2D), a blow-molded article was obtained by molding in a similar mannerto Example 7 and was evaluated.

Table 5 shows evaluation results of characteristics of the resultingblow-molded article.

The phosphorus content of the polyester composition was 0 ppm, thedifference (A_(t)−A₀) between the acetaldehyde contents before and afterinjection molding was 23 ppm, the AA content of the blow-molded articlewas 29 ppm, the FA content was 4.8 ppm, and transparency was “C(transparency is poor and colored non-melted matter is observed)” andsensory test was “B” which were bad, so that the article lacked inpracticality.

COMPARATIVE EXAMPLE 7

Using 30 parts by weight of Ny-MXD6 (2H) per 100 parts by weight of PET(2E), a blow-molded article was obtained by molding in a similar mannerto Example 7 and was evaluated.

Table 5 shows evaluation results of characteristics of the resultingblow-molded article.

The phosphorus content of the polyester composition was 211 ppm, thedifference (A_(t)−A₀) between the acetaldehyde contents before and afterinjection molding was 12 ppm, the AA content of the blow-molded articlewas 15 ppm, and the FA content was 4.1 ppm, but transparency was “C(transparency is poor)” and evaluation in sensory test was “CC” whichwere bad, so that the article lacked in practicality.

COMPARATIVE EXAMPLE 8

Using 100 parts by weight of PET (2D), a blow-molded article wasobtained by molding in a similar manner to Example 7 and was evaluated.

Table 5 shows evaluation results of characteristics of the resultingblow-molded article.

EXAMPLE 10

Using 10 parts by weight of Ny-MXD6 (2F) per 100 parts by weight of PET(2A), a blow-molded article was obtained by molding according to themethod of the, evaluation method (15) and evaluation on mold fouling wasalso carried out.

Table 6 shows evaluation results of characteristics and mold fouling ofthe resulting blow-molded article.

The difference (A_(t)−A₀) between the acetaldehyde contents of thepolyester composition before and after injection molding was 5 ppm, thephosphorus content of the blow-molded article was 44 ppm, the AA contentof the blow-molded article was 8 ppm, the ΔAA content was 11 ppm, the FAcontent was 0.2 ppm, the content of cyclic ester trimer was 0.32% byweight, the increase of the content of cyclic ester trimer (ΔCT₂ amount)was 0.05% by weight, the CM content was 510 ppm, evaluation in sensorytest was “A”, transparency was “A”, and no attached matter to the moldwas observed.

EXAMPLE 11

Using 20 parts by weight of Ny-MXD6 (2G) per 100 parts by weight of PET(2B), a blow-molded article was obtained by molding according to themethod of the evaluation method (15) and evaluation on mold fouling wasalso carried out.

Table 6 shows evaluation results of characteristics and mold fouling ofthe resulting blow-molded article.

The difference (A_(t)−A₀) between the acetaldehyde contents of thepolyester composition before and after injection molding was 5 ppm, thephosphorus content of the blow-molded article was 83 ppm, the AA contentof the blow-molded article was 8 ppm, the ΔAA content was 11 ppm, the FAcontent was 0.1 ppm, the content of cyclic ester trimer was 0.37% byweight, the increase of the content of cyclic ester trimer (ΔCT₂ amount)was 0.10% by weight, the CM content was 1000 ppm, evaluation in sensorytest was “A”, transparency was “A”, and no attached matter to the moldwas observed.

EXAMPLE 12

Using 30 parts by weight of Ny-MXD6 (2G) per 100 parts by weight of PET(2A), a blow-molded article was obtained by molding according to themethod of the evaluation method (15) and evaluation on mold fouling wasalso carried out. Table 6 shows evaluation results of characteristicsand mold fouling of the resulting blow-molded article.

The difference (A_(t)−A₀) between the acetaldehyde contents of thepolyester composition before and after injection molding was 4 ppm, thephosphorus content of the blow-molded article was 104 ppm, the AAcontent of the blow-molded article was 6 ppm, the ΔAA content was 9 ppm,the FA content was 0.1 ppm, the content of cyclic ester trimer was 0.32%by weight, the increase of the content of cyclic ester trimer (ΔCT₂amount) was 0.05% by weight, the CM content was 1300 ppm, evaluation insensory test was “A”, transparency was “A”, and no attached matter tothe mold was observed.

COMPARATIVE EXAMPLE 9

Using 0.05 part by weight of Ny-MXD6 (2I) per 100 parts by weight of PET(2D), a blow-molded article was obtained by molding according to themethod of the evaluation method (15) and evaluation on mold fouling wasalso carried out. Table 6 shows evaluation results of characteristicsand mold fouling of the resulting blow-molded article.

The difference (A_(t)−A₀) between the acetaldehyde contents of thepolyester composition before and after injection molding was 25 ppm, thephosphorus content of the blow-molded article was 0 ppm, the AA contentof the blow-molded article was 40 ppm, the ΔAA content was 35 ppm, theFA content was 6.5 ppm, the content of cyclic ester trimer was 0.65% byweight, the increase of the content of cyclic ester trimer (ΔCT₂ amount)was 0.51% by weight, evaluation in sensory test was “C”, andtransparency was “C (transparency is poor and colored non-melt matter isobserved)” which were bad, and mold fouling was severe.

COMPARATIVE EXAMPLE 10

Using 30 parts by weight of Ny-MXD6 (2H) per 100 parts by weight of PET(2E), a blow-molded article was obtained by molding according to themethod of the evaluation method (15) and evaluation on mold fouling wasalso carried out. Table 6 shows evaluation results of characteristicsand mold fouling of the resulting blow-molded article.

The difference (A_(t)−A₀) between the acetaldehyde contents of thepolyester composition before and after injection molding was 7 ppm, thephosphorus content of the blow-molded article was 211 ppm, the AAcontent of the blow-molded article was 13 ppm, the ΔAA content was 17ppm, the FA content was 4.2 ppm, the content of cyclic ester trimer was0.70% by weight, the increase of the content of cyclic ester trimer(ΔCT₂ amount) was 0.54% by weight, the CM content was 4000 ppm,evaluation in sensory test was “CC”, and transparency was “C(transparency is poor)” which were bad, and mold fouling was severe.TABLE 5 Characteristics of polyester compositions and blow-moldedarticles Polyester Blow-molded article composition Oxygen Phos-permeability NY-MXD6 phorus AA con- (cc/one PET (part by (part con-tenttent FA content Trans- Sensory container · 24 hr · weight) by weight)(ppm) A_(t)-A₀ (ppm) (ppm) parency test atm) Example 7 (2C) 100 (2F) 236 9 10 0.4 AA AA — Example 8 (2C) 100 (2F) 10 47 6 9 0.1 A AA 0.30Example 9 (2C) 100 (2G) 30 107 5 6 0.1 A A 0.20 Comparative (2D) 100(2I) 10 0 23 29 4.8 C B 0.30 Example 6 Comparative (2E) 100 (2H) 30 21112 15 4.1 C CC 0.17 Example 7 Comparative (2D) 100 — — 0 31 45 6.2 AA CC0.58 Example 8

TABLE 6 Characteristics of blow-molded articles Characteristics of blowmold articles Oxygen CT permeability NY-MXD6 Na AA FA content ΔCT₂ CMSen- (cc/one Mold PET (part by (part content content ΔAA content (% by(% by content Trans- sory container · 24 foul- weight) by weight) (ppm)(ppm) (ppm) (ppm) weight) weight) (ppm) parency test hr · atm) ingExample 10 (2A) 100 (2F) 10 44 8 11 0.2 0.32 0.05 510 A A 0.31 AAExample 11 (2B) 100 (2G) 20 83 8 11 0.1 0.37 0.10 1000 A A 0.20 ◯Example 12 (2A) 100 (2G) 30 104 6 9 0.1 0.32 0.05 1300 A A 0.17 AAComparative (2D) 100 (2I) 0.05 0 40 35 6.5 0.65 0.51 10 C C 0.57 CExample 9 Comparative (2E) 100 (2H) 30 211 13 17 4.2 0.70 0.54 4000 C CC0.17 C Example 10CT = cyclic ester trimerCM = cyclic amide monomer

EXAMPLE 13

Using 0.5 part by weight of Ny-MXD6 (3E) per 100 parts by weight of PET(3A), a molded plate and a blow-molded article were obtained by moldingaccording to the method of the evaluation method (15) and wereevaluated.

Table 7 shows characteristics and evaluation results of the resultingmolded plate and blow-molded article.

The molded plate obtained by injection molding was satisfactory in bothof color tone and haze. Further, the AA content of the blow-moldedarticle was 7 ppm, the FA content was 0.1 ppm, evaluation in sensorytest was 0.7, and the appearance was transparent within a practicalrange.

EXAMPLE 14

Using 3.0 parts by weight of Ny-MXD6 (3E) per 100 parts by weight of PET(3A), a molded plate and a blow-molded article were obtained by moldingaccording to the method of the evaluation method (15) and wereevaluated.

Table 7 shows characteristics and evaluation results of the resultingmolded plate and blow-molded article.

The molded plate obtained by injection molding was satisfactory in bothof color tone and haze. Further, the AA content of the blow-moldedarticle was 6 ppm, the FA content was 0.08 ppm, evaluation in sensorytest was 0.6, and the appearance was transparent within a practicalrange.

EXAMPLE 15

Using 3.0 parts by weight of Ny-MXD6 (3D) per 100 parts by weight of PET(3A), a molded plate and a blow-molded article were obtained by moldingaccording to the method of the evaluation method (15) and wereevaluated. Table 7 shows characteristics and evaluation results of theresulting molded plate and blow-molded article.

The molded plate obtained by injection molding was satisfactory in bothof color tone and haze. Further, the AA content of the blow-moldedarticle was 7 ppm, the FA content was 0.07 ppm, evaluation in sensorytest was 0.6, and the appearance was transparent within a practicalrange.

EXAMPLE 16

Using 20.0 part by weight of Ny-MXD6 (3E) per 100 parts by weight of PET(3A), a molded plate and a blow-molded article were obtained by moldingaccording to the method of the evaluation method (15) and wereevaluated. Table 7 shows characteristics and evaluation results of theresulting molded plate and blow-molded article.

The molded plate obtained by injection molding was satisfactory in bothof color tone and haze. Further, the AA content of the blow-moldedarticle was 6 ppm, the FA content was 0.05 ppm, evaluation in sensorytest was 0.7, and the appearance was transparent within a practicalrange.

COMPARATIVE EXAMPLE 11

Using 3.0 parts by weight of Ny-MXD6 (3E) per 100 parts by weight of PET(3B), a molded plate and a blow-molded article were obtained by moldingaccording to the method of the evaluation method (15) and wereevaluated.

Table 7 shows characteristics and evaluation results of the resultingmolded plate and blow-molded article.

The molded plate obtained by injection molding had a low Color-L valueand was darkly. Further, the AA content of the blow-molded article was 9ppm, the FA content was 0.5 ppm, and evaluation in sensory test was 0.8,which were satisfactory, but transparency was bad.

COMPARATIVE EXAMPLE 12

Using 20.0 part by weight of Ny-MXD6 (3E) per 100 parts by weight of PET(3C), a molded plate and a blow-molded article were obtained by moldingaccording to the method of the evaluation method (15) and wereevaluated.

Table 7 shows characteristics and evaluation results of the resultingmolded plate and blow-molded article.

The molded plate obtained by injection molding was satisfactory in colortone but the haze value was high. Further, the AA content of theblow-molded article was 10 ppm, the FA content was 0.3 ppm, evaluationin sensory test was 0.8, which were satisfactory, but transparency wasbad. TABLE 7 Example Example Example Example Comparative ComparativeItem 13 14 15 16 Example 11 Example 12 Polyester PET(3A) (part byweight) 100 100 100 100 composition PET(3B) (part by weight) 100 PET(3C)(part by weight) 100 Ny-MXD6 (3E) (part by 3.0 weight) Ny-MXD6 (3E)(part by 0.5 3.0 20.0 3.0 20.0 weight) Molded Haze (%, 2 mm) 0.6 1.0 0.815.0 22.4 32.1 plate Color tone (Color-L value) 89.1 88.5 88.7 86.4 78.987.7 (2 mm) At-A0(ppm) 5 4 4 3 7 6 Blow- AA content (ppm) 7 6 7 6 9 10molded FA content (ppm) 0.1 0.08 0.07 0.05 0.5 0.3 article TransparencyA A A A C C Sensory test 0.7 0.6 0.6 0.7 0.8 0.8 Oxygen permeability — —— 0.20 — — (cc/one container · 24 hr · atm)

EXAMPLE 17

Using 1.0 part-by weight of Ny-MXD6 (4b) and 0.03 part by weight of2-aminobenzamide (a reagent manufactured by Tokyo Kasei Kogyo Co., Ltd.)per 100 parts by weight of PET (4a), a blow-molded article was obtainedby molding according to the method of the evaluation method (15) and theCM content, the CT content, and the AA content of the molded articlewere measured. In addition, evaluation on mold fouling was also carriedout.

Table 8 shows characteristics of the resulting blow-molded article andevaluation results of mold fouling thereof.

PET (4a) is one obtained by polymerization in a continuous meltpolycondensation-solid phase polymerization apparatus and subsequenttreatment with hot water in ion-exchange water at about 90° C. for 3hours, and has the following characteristics: Ge remaining amount of 40ppm, phosphorus remaining amount of 35 ppm, IC of 0.74 dl/g, AA contentof 2.4 ppm, CT content of 0.31% by weight, and ΔCT₁ of 0.04% by weight.Further, Ny-MXD6 (4b) has Rv of 1.8 and CM content of 2.3% by weight.

EXAMPLES 18 TO 20 AND COMPARATIVE EXAMPLES 13 AND 14

Each blow-molded articles was produced in the ratios shown in Table 8 ina similar manner to Example 1 and was evaluated. Table 8 shows theresults. A reagent manufactured by Tokyo Kasei Kogyo Co., Ltd. was usedas 1,8-diaminonaphthalate. TABLE 8 Comparative Comparative ExampleExample Example Example Example Example 17 18 19 20 13 14 PolyesterPET(4a) (part by weight) 100 100 100 100 100 100 composition Ny-MXD6(4c) (part by 1.0 0.5 0.5 10.0 weight) 2-Aminobenzamide (part 0.03 0.050.05 1.2 by weight) 1,8-diamino-naphthalate 0.10 (part by weight) MoldedHaze (%, 5 mm) 7.4 5.8 5.1 15.2 22.0 1.5 plate Blow- AA content (ppm) 78 8 7 10 28 molded FA content (ppm) 0.2 0.1 0.1 0.1 4.2 6.7 article CTcontent (% by weight) 0.35 0.37 0.38 0.36 0.35 0.37 CM total content (%by 0.02 0.01 0.01 0.23 — — weight) Mold fouling A A A A B A TransparencyA A A A C A Yellowing degree A A A A C A Sensory test 0.7 0.7 0.6 0.72.6 2.5 Oxygen permeability — — — 0.20 — — (cc/one contain-er · 24 hr ·atm)<Effects of the Invention>

According to the present invention, a polyester composition excellent intransparency, thermal stability, and flavor retention, or transparency,thermal stability, flavor retention, and gas barrier properties isobtained. The polyester composition of the invention is extremelysuitable as a packaging material for drinks such as beverages asmentioned above.

1. A polyester composition comprising 100 parts by weight of athermoplastic polyester and 0.1 to 50 parts by weight of a partiallyaromatic polyamide, wherein the content of an alkali metal atom in thepolyester composition is within the range of 0.1 to 300 ppm.
 2. Apolyester composition comprising 100 parts by weight of a thermoplasticpolyester and 0.1 to 50 parts by weight of a partially aromaticpolyamide, wherein the content of phosphorus atom in the polyestercomposition is within the range of 5 to 200 ppm.
 3. The polyestercomposition according to claim 1, wherein the content of phosphorus atomin the polyester composition is within the range of 5 to 200 ppm.
 4. Apolyester composition comprising 100 parts by weight of a thermoplasticpolyester comprising a dicarboxylic acid component mainly comprising anaromatic dicarboxylic acid or an ester-forming derivative thereof and aglycol component mainly comprising ethylene glycol, and 0.01 to 30 partsby weight of a partially aromatic polyamide, wherein the Color-L valueof a molded article obtained by injection molding of the polyestercomposition at a molding temperature of 290° C. is 80.0 or more and thehaze thereof is 20% or less.
 5. The polyester composition according toclaim 4, wherein the content of antimony atom is 200 ppm or less.
 6. Thepolyester composition according to claim 4, wherein the content of analkali metal atom is from 0.1 to 300 ppm and the content of phosphorusatom is from 5 to 200 ppm in the polyester composition.
 7. A polyestercomposition comprising 100 parts by weight of a thermoplastic polyester,0.01 to 100 parts by weight of a partially aromatic polyamide, and5×10⁻⁴ to 1 part by weight of an amino group-containing compound.
 8. Thepolyester composition according to claim 1, wherein the partiallyaromatic polyester is an m-xylylene group-containing polyamide.
 9. Thepolyester composition according to claim 1, wherein the thermoplasticpolyester is a polyester comprising ethylene terephthalate as a mainrepeating unit.
 10. The polyester composition according to claim 1,wherein the difference (A_(t)−A₀) between the acetaldehyde content(A_(t)) (ppm) in an molded article obtained by injection molding of thepolyester composition and the acetaldehyde content (A₀) (ppm) of thepolyester composition before injection molding is 20 ppm or less. 11.The polyester composition according to claim 1, wherein the content of acyclic trimer derived from the thermoplastic polyester is 0.7% by weightor less.
 12. The polyester composition according to claim 1, wherein theincrease of a cyclic trimer derived from the thermoplastic polyesterduring melting treatment at 290° C. for 30 minutes is 0.4% by weight orless.
 13. A polyester packaging material, which is obtained by moldingthe polyester composition according to claim
 1. 14. The polyesterpackaging material according to claim 13, wherein the packaging materialis at least any one of blow-molded articles, sheet articles, and films.15. The polyester composition according to claim 2, wherein thepartially aromatic polyester is an m-xylylene group-containingpolyamide.
 16. The polyester composition according to claim 4, whereinthe partially aromatic polyester is an m-xylylene group-containingpolyamide.
 17. The polyester composition according to claim 7, whereinthe partially aromatic polyester is an m-xylylene group-containingpolyamide.
 18. The polyester composition according to claim 2, whereinthe thermoplastic polyester is a polyester comprising ethyleneterephthalate as a main repeating unit.
 19. The polyester compositionaccording to claim 4, wherein the thermoplastic polyester is a polyestercomprising ethylene terephthalate as a main repeating unit.
 20. Thepolyester composition according to claim 7, wherein the thermoplasticpolyester is a polyester comprising ethylene terephthalate as a mainrepeating unit.
 21. The polyester composition according to claim 2,wherein the difference (A_(t)−A₀) between the acetaldehyde content(A_(t)) (ppm) in an molded article obtained by injection molding of thepolyester composition and the acetaldehyde content (A₀) (ppm) of thepolyester composition before injection molding is 20 ppm or less. 22.The polyester composition according to claim 4, wherein the difference(A_(t)−A₀) between the acetaldehyde content (A_(t)) (ppm) in an moldedarticle obtained by injection molding of the polyester composition andthe acetaldehyde content (A₀) (ppm) of the polyester composition beforeinjection molding is 20 ppm or less.
 23. The polyester compositionaccording to claim 7, wherein the difference (A_(t)−A₀) between theacetaldehyde content (A_(t)) (ppm) in an molded article obtained byinjection molding of the polyester composition and the acetaldehydecontent (A₀) (ppm) of the polyester composition before injection moldingis 20 ppm or less.
 24. The polyester composition according to claim 2,wherein the content of a cyclic trimer derived from the thermoplasticpolyester is 0.7% by weight or less.
 25. The polyester compositionaccording to claim 4, wherein the content of a cyclic trimer derivedfrom the thermoplastic polyester is 0.7% by weight or less.
 26. Thepolyester composition according to claim 7, wherein the content of acyclic trimer derived from the thermoplastic polyester is 0.7% by weightor less.
 27. The polyester composition according to claim 2, wherein theincrease of a cyclic trimer derived from the thermoplastic polyesterduring melting treatment at 290° C. for 30 minutes is 0.4% by weight orless.
 28. The polyester composition according to claim 4, wherein theincrease of a cyclic trimer derived from the thermoplastic polyesterduring melting treatment at 290° C. for 30 minutes is 0.4% by weight orless.
 29. The polyester composition according to claim 7, wherein theincrease of a cyclic trimer derived from the thermoplastic polyesterduring melting treatment at 290° C. for 30 minutes is 0.4% by weight orless.
 30. A polyester packaging material, which is obtained by moldingthe polyester composition according to claim
 2. 31. A polyesterpackaging material, which is obtained by molding the polyestercomposition according to claim
 4. 32. A polyester packaging material,which is obtained by molding the polyester composition according toclaim 7.